IRON  AND  STEEL 


*$£  Qruw-Jf ill  Book  60  7m 

PUBLISHERS     OF     BOOKS      F  O  R_, 

Coal  Age  •»  Electric  Railway  Journal 
Electrical  World  v  Engineering,  News-Record 
American  Machinist  v  The  Contractor 
Engineering 8 Mining  Journal  ^  Power 
Metallurgical  6  Chemical  Engineering 
Electrical  Merchandising 


IRON  AND  STEEL 

(A  POCKET  ENCYCLOPEDIA) 


INCLUDING  ALLIED  INDUSTRIES 
AND  SCIENCES 


BY 

HUGH  P.  TIEMANN,  B.S.,  A.M. 


WITH  AN  INTRODUCTION 
BY 

HENRY  MARION  HOWE 


SECOND  EDITION 
REVISED,  ENLARGED  AND  ENTIRELY  RESET 


FIRST  IMPRESSION 


McGRAW-HILL   BOOK   COMPANY,  INC. 
239  WEST  39TH   STREET,  NEW  YORK 


LONDON:  HILL  PUBLISHING  CO.,  LTD. 
6  &  8  BOUVERIE  ST.,  E.G. 

1919 


/LOJLI 


COPYRIGHT,  1919,  BY  THE 
MCGRAW-HILL  BOOK  COMPANY,  INC. 


,ij.:i  ,.TC  3i;?:iv7vjd  ^  -jc,  o 

THE    MAPLE    PRESS    YORK 


INTRODUCTION 


IT  is  with  gratitude  as  a  reader,  pride  as  a  teacher,  and  pleasure 
as  a  friend  that  I  write  a  word  of  introduction  to  this  admirable 
work  of  my  former  pupil  and  long-time  friend,  the  Author. 

The  jargon  of  the  millman,  like  that  of  the  philosopher,  is  a 
deplorable  necessity.  It  is  a  collection  of  invaluable  special  tools 
for  special  men  doing  special  work.  When  the  dentist  and  the 
obstetrician  regard  the  unfathomable  mysteries  of  each  other's 
"kits,"  each  has  the  consolation  that  he  need  not  attempt  the  fath- 
oming. But  alas,  you  and  I  cannot  thus  escape  each  other's  jargon, 
for  the  metallographist  must  needs  learn  from  the  millman  and  the 
millman  from  the  metallographist,  and  each  has  become  the  slave  of 
his  own  tools,  his  own  jargon.  He  talks  and  perhaps  thinks  in  terms 
of  it,  if  indeed  we  think  in  any  language,  which  I  doubt  At  least, 
if  he  thinks  in  any  language  it  is  in  his  jargon.  Life  is  too  short, 
patience  too  flimsy,  to  permit  our  forcing  our  thoughts  into  others' 
minds  by  means  of  any  tools  other  than  our  own  jargon.  The 
Author  gives  me  an  admirable  case  in  point. 

Foreman:  "How  does  this  steel  work?" 

Heater:  "If  you  don't  wash  it,  it  won't  clean." 

This  is  "short  hand"  for:  "The  iron  oxide  or  'scale'  which  forms 
on  the  surface  of  this  steel  adheres  so  firmly  that,  unless  it  is  heated 
so  highly  that  it  melts,  some  of  it  will  cleave  to  the  metal  during 
the  operation  of  rolling,  and  hence  will  deface  the  finished  plates 
into  which  the  steel  is  to  be  rolled."  The  heater's  words  are  not 
English;  they  are  jargon,  and  it  is  proper  that  they  should  be.  If 
he  persisted  in  translating  them  into  English  as  I  have  done,  and  in 
talking  English  in  general,  he  would  simply  justify  the  dismissal 
which  would  surely  come.  The  guild  has  evolved  its  jargon  for  its 
own  use.  To  replace  it  with  the  King's  English  would  be  about 
as  unwise  as  to  replace  it  with  French  or  modern  Greek,  or  to  replace 
"short  hand"  with  "long  hand"  in  the  reporting  of  debate. 

When  the  metallographist  and  millman  meet,  it  is  as  the  meeting 
of  French  and  Greek.  The  millman  scolds  the  metallographist, 
yes,  and  I  have  had  to  endure  with  my  scanty  patience  many  such 
scoldings  for  deliberately  inventing  jargon,  useful  for  the  metallo- 
graphic  guild,  but  a  stumbling  block  to  the  millman.  Of  course 
it  is  not  I  but  the  nature  of  things  that  ought  to  be  scolded;  but 
then  it  is  pleasanter  and  less  transparently  foolish  to  scold  me, 
especially  if  I  have  previously  earned  your  gratitude  by  disen- 
tangling some  of  your  fallacies  and  sophisms. 


392156 


vi  INTRODUCTION 

Now  here  comes  the  gallant  Author  to  the  aid  of  fumbling  metal- 
lographist  and  irritated  millman.  With  infinite  pains,  ingenuity, 
and  skill  he  blesses  both  where  they  had  banned  each  other,  and 
enables  the  brothers  to  dwell  together  in  harmony,  unfolding  to  each 
the  jargon  of  the  other  by  means  of  a  tri-lingual  dictionary,  trans- 
lating the  jargons  of  both  into  the  common  language,  English. 

Nor  are  they  alone  his  debtors.  Having  long  lived  a  metallog- 
raphist  and  a  teacher  among  the  millmen,  he  discloses  clearly, 
tersely,  and  graphically  the  manners  and  customs  of  the  millmen, 
to  wit  the  how  and  the  why  of  their  actual  practice,  as  only  a  resi- 
dent can  know  it.  In  short,  he  describes  the  actual  metallurg- 
ical operations  and  apparatus  in  a  way  which  seems  to  me  most 
admirable. 

I  .commend  the  book  without  reserve  to  the  whole  family  of  steel 
metallurgists,  be  they  millmen,  metallographists,  teachers,  or 
students. 

HENRY  M.  HOWE. 

-fil-iii  rmt  jqrnojtP  jon  JO-JCT  o:i  j&nt  mnu'oii!  > 

iTo-'-  <>'••  nito  ri'>K3  tJji^i  >;;;!;  .toncur.*  I  !>•;>;  no-r  .?.K\L  n;8      .filrrr 


t/"  jdj/ob  L  fioirtv/  .*>^f;ij«(:rtf  '/nr;  ni  ^rd-'It  ->*r 
''n-J  --:  -J^.J  .no^id  ?:rt  ru  ?.j  !i  ><jum'ru;f  v:tj? 
>  ohit  '^rixiioilt  UJT*  ^njaiol  TJJCJ  jhrn  K|  ol  .v^m 


riaifW 
:  i. rod's 


;»;(  H 


PREFACE  TO  SECOND  EDITION 


THE  present  revision  is  the  result,  not  only  of  certain  omissions 
and  shortcomings  in  the  first  edition,  but  also  of  the  friendly 
reception  and  the  helpful  criticism  accorded  it. 

The  vast  amount  of  time  consumed — in  no  way  evident  from 
the  result — in  consulting  references  and  authorities,  collecting  data, 
and  condensing  and  practically  rewriting  the  whole  of  the  text,  all 
of  which  had  to  be  done  without  interference  with  regular  business, 
prevented  the  completion  of  the  task  at  an  earlier  date.  It  is 
hoped  that  an  improvement  will  be  found  both  in  regard  to  the 
additional  information  and  the  method  of  treatment.  The  num- 
ber of  terms,  and  the  text  also,  has  been  increased  about  fifty  per 
cent. 

The  general  processes  of  manufacture  have  undergone  but  little 
change,  the  principal  development  being  in  the  greatly  increased 
use  of  the  electric  furnace.  The  chief  increase  in  the  text  is  due 
to  more  extended  discussions  of  subjects,  such  as  heat  treatment, 
physical  properties,  and  testing,  and  to  the  numerous  investiga- 
tions of  the  more  theoretical  aspects  of  the  subject,  particularly 
those  included  under  metallography. 

For  the  benefit  of  those  little  versed  in  the  metallurgy  of  iron 
and  steel,  and  who  may  desire  a  guide  to  a  more  sequential — and 
hence  logical — study  than  is  afforded  by  the  alphabetical  arrange- 
ment of  the  text  (which  still  seems  best  for  ready  reference)  a  brief 
outline  of  the  metallurgy  of  iron  and  steel  has  been  prepared  which 
will  be  found  immediately  preceding  the  text. 

Among  a  number  of  kind  friends  whose  assistance  is  deeply  ap- 
preciated, the  author  desires  to  express  his  thanks  especially  to 
D.  M.  Buck  (Corrosion  and  Protection),  L.  J.  Gray  (Gages),  E.  S. 
Humphreys  (Sheets  and  Tin  Plate),  E.  A.  Kebler  (Pig  Iron),  and 
J.  O.  Leech  (Specifications);  the  opportunity  cannot  be  allowed  to 
pass  of  calling  attention  to  the  cordial  cooperation  of  the  publishers, 
whose  assistance  in  practical  suggestions  and  care  in  the  make-up 
of  the  book  have  contributed  in  no  small  degree  to  whatever  success 
it  has  achieved. 

H.  P.  T. 

PITTSBURGH,  PA., 
December,  1918. 


vn 


PREFACE  TO  FIRST  EDITION 


OWING  to  the  close  relationship  with  other  industries,  such  as 
coal,  coke,  etc.,  and  from  the  fact  that  certain  branches  of  science 
are  involved  in  metallurgy,  terms  applying  to  these  have  been  in- 
cluded in  this  book,  in  so  far  as  they  are  commonly  met  with  in  the 
literature  of  iron  and  steel.  In  general,  subjects  of  a  mechanical 
or  of  an  engineering  nature  have  not  been  considered,  as  they  are 
dealt  with  in  the  handbooks  devoted  especially  to  them.  It  may 
be  found,  however,  that  in  some  cases  subjects  have  been  incorpo- 
rated which  seem  superfluous  in  a  work  of  this  character. 

It  has  been  the  endeavor  to  make  the  book  as  compact  as  possible, 
at  the  same  time  giving  sufficiently  full  explanations  for  ordinary 
purposes  so  that  to  the  metallurgist  who  wishes  to  refresh  his  mind 
on  _some  term  rarely  used,  and  to  the  person  only  slightly  familiar 
with  the  ground,  it  may  prove  equally  useful. 

The  general  treatment,  then,  is  a  combination  of  a  dictionary,  a 
cyclopedia,  and  a  handbook,  possessing  as  well  as  omitting  some 
of  the  features  of  all.  The  definitions  or  descriptions  of  isolated 
terms  or  processes  are  found  under  the  respective  headings,  while 
those  employed  .in  connection  with  some  special  subject  or  process 
are  found  under  the  latter,  reference  being  made,  as  a  rule,  by  page 
numbers  instead  of  by  titles.  In  this  way,  the  reader  who  desires 
enlightenment  upon  a  single  point,  as  well  as  he  who  is  unfamiliar 
with  the  subject  as  a  whole  or  who  wishes  to  learn  the  terms  used 
in  a  certain  process,  may  do  so  as  readily  and  as  simply  as  possible. 

Among  the  many  authorities  consulted,  the  most  important  is 
unquestionably  the  Journal  of  the  Iron  and  Steel  Institute,  which 
is  a  veritable  mine  of  information.  The  writer  whose  books  have 
been  drawn  upon  most  largely  is  Prof.  Henry  M.  Howe,  who  pos- 
sesses in  the  highest  degree  the  unusual  and  happy  faculty  of  ex- 
pressing what  he  has  to  say  both  clearly  and  concisely. 

The  Author's  thanks  are  due  to  many  good  friends  for  the 
timely  criticism  and  advice  which  they  were  ever  ready  to  give. 
Among  those  to  whom  he  is  especially  indebted  are  the  following: 
J.  W.  Benner,  W.  A.  Bostwick,  Prof.  William  Campbell,  Prof.  Henry 
M.  Howe,  E.  T.  Ickes,  Eliot  A.  Kebler,  C.  F.  W.  Rys,  and  Bradley 
Stoughton. 

In  conclusion,  the  Author  will  be  most  grateful  to  any  one  calling 
his  attention  to  errors  of  omission  as  well  as  of  commission. 

H.  P.  T. 

PITTSBURGH,  PA., 
November,  1910. 

ix 


-'oiTKl/T 


OUTLINE  OF 
THE  METALLURGY  OF  IRON  AND  STEEL 


The  term  iron  has  such  a  variety  of  applications  that,  if  used  by 
itself,  the  exact  meaning  cannot  be  determined.  In  its  chemical 
sense  it  refers  to  the  element  (see  Chemistry),  either  isolated  or 
combined  with  other  elements;  e.g.,  the  percentage  of  the  element 
present  in  metallic  substances,  iron  ores,  etc.  In  its  metallic  con- 
dition the  carbon  content  (either  expressed  or  implied)  is  the  de- 
termining factor.  In  this  case  "iron"  may  refer  to  (a)  the  nearly 
pure  substance  (see  Electrolytic  Iron);  (b)  the  product  nearly  free 
from  carbon,  more  specifically  known  as  wrought  (malleable}  iron  or 
puddled  iron;  or  (c)  where  the  carbon  content  is  high,  termed  cast 
iron  or  pig  iron.  Steel  is  the  present  name  for  iron  produced  by  any 
process,  in  a  fluid  condition  thereby  permitting  nearly  complete 
elimination  of  slag,  and  containing  any  amount  of  carbon  up  to  a 
content  where  it  can  no  longer  be  usefully  worked.  Before  the 
appearance  of  the  Bessemer  process,  the  classification  provided  for 
(a)  iron,  low  in  carbon,  which  was  malleable  and  could  not  be  use- 
fully hardened,  produced  by  a  direct  process  or  by  puddling;  (6) 
steel  (higher  in  carbon)  which  was  also  malleable  but  could  be  use- 
fully hardened,  produced  in  the  same  way  as  iron  and  called  wrought 
steel;  by  the  conversion  (carburization)  of  wrought  iron  into  steel 
by  cementation  (q.v.),  the  product  being  denominated  blister  bars 
or  cement  bars  and  used  as  such  (blister  steel)  or  remelted  in  the 
crucible  process  for  crucible  steel  or  cast  steel;  (c)  cast  iron  as  described 
above,  so  named  because  it  could  not  be  worked  but  could  be  given 
the  desired  form  only  by  casting  when  molten  into  molds. 

Metallic  iron  or  steel  is  not  found  naturally  in  that  condition. 
An  apparent  exception  is  the  case  of  certain  meteorites  (q.v.).  As 
it  exists  in  chemical  combination  with  other  elements,  principally 
as  an  oxide,  and  mechanically  mixed  with  a  certain  amount  of 
earthy  matter  (chiefly  sand  or  clay),  occurring  in  deposits  known 
as  ore  (see  Iron  Ore),  it  becomes  necessary  to  reduce  it  to  the 
metallic  state  by  an  operation  known  as  smelting.  This  is  accom- 
plished practically  exclusively  by  carbon  occurring  in  some  form  of 
solid  fuel,  such  as  coke,  coal,  or  charcoal,  which  serves  not  only  as 
the  medium  of  reduction,  but  also  for  producing  by  combustion 
the  heat  (temperature)  required  to  carry  on  this  reaction.  The 
heat  for  this  and  other  processes  is  occasionally  supplied  by  some 
other  agency  such  as  electricity  (see  Electric  Processes). 


xn          THE  METALLURGY  OF  IRON  AND  STEEL 

The  quality  of  an  ore  can. in  various  cases  be  materially  improved 
by  roasting  to  burn  away  impurities,  or  by  washing  away  a  con- 
siderable portion  of  the  earthy  matter  or  gangue  (see  Ore).  It  may 
also  be  desirable  to  agglomerate  fine  ore  or  similar  material  into 
hard  tenacious  pieces  or  lumps  (see  Briquette). 

In  the  production  of  metallic  iron  two  conditions  are  necessary: 

1.  Reduction  of  the  iron  oxide,  i.e.,  elimination  of  the  oxygen 
with  which  it  is  chemically  combined;  effected  by  part  of  the  carbon 
of  the  fuel. 

2.  Separation  and  removal  of  the  gangue  with  which  it  is  mechan- 
ically mixed;  usually  by  the  addition  of  a  substance  or  flux  with 
which  it  unites  to  form  a  more  fusible  compound  or  slag. 

Iron  can  be  partially  reduced  at  relatively  low  temperatures,  e.g., 
by  carbon  monoxide  gas,  and  completely  reduced  at  somewhat 
higher  temperatures  but  still  considerably  below  its  melting  point, 
by  contact  with  hot  carbonaceous  matter.  It  is  the  latter  method 
which  was  originally  employed  because  the  necessary  temperature 
was  readily  secured  by  simple  equipment  such  as  a  hole  dug  in  a 
hillside  where  the  prevailing  winds  supplied  the  air  for  combustion 
through  suitable  apertures  in  the  roof.  Soon,  however, 'advances 
were  made  by  developing. a  fireplace  or  hearth  where  charcoal  could 
be  burned  intermixed  with  rich  ore.  Part  of  the  ore  was  reduced 
and  part  was  lost  in  slagging  off  the  gangue.  The  reduced  pasty 
iron  collected  at  the  bottom  together  with  molten  slag  or  portions 
of  the  original  charge:  additional  fuel  and  ore  could  be  thrown  in 
through  an  opening  in  the  front.  However,  as  the  size  of  the 
equipment  was  increased  it  was  found  advantageous  to  do  the 
charging  through  a  hole  in  the  top  or  stack. 

When  natural  draft  failed  to  supply  air  at  the  necessary  rate  and 
pressure,  bellows  were  substituted,  and  these,  in  turn,  were  replaced 
by  some  form  of  blowing  engine  (see  Direct  Processes).  Greater 
height  of  stack,  better  insulation  against  loss  of  heat,  and  more 
rapid  combustion  all  led  to  increased  temperature  (see  Heat),  and 
also  more  and  more  carbon  was  absorbed  by  the  metal.  Finally 
the  condition  was  reached  where  the  melting  point  of  the  iron  was 
lowered  sufficiently  by  the  increased  absorption  of  carbon  to  be 
below  the  temperature  of  reduction,  and  the  product  was  then 
obtained  in  a  liquid  (molten)  state.  It  was  accordingly  run  or 
poured  (cast)  into  suitable  molds  and  hence  was  termed  cast  iron. 

While  at  first,  due  to  variations  in  temperature,  the  iron  from 
the  same  furnace  was  sometimes  pasty  and  sometimes  molten,  it 
was  quickly  realized  that  the  greatest  output  and  ease  of  handling 
resulted  from  the  latter  condition,  hence  the  necessary  steps  were 
taken  to  make  this  condition  permanent  and  resulted  in  the  devel- 
opment of  the  present  blast  furnace  (q.v.). 

At  the  high  temperature  of  the  blast  furnace  nearly  all  the  iron, 
manganese,  and  phosphorus  are  reduced  and  also  certain  proportions 
of  silicon,  sulphur,  and  other  elements  present.  The  high  contents 
of  elements  other  than  iron  prevent  cast  iron  from  being  usefully 
malleable  at  any  temperature,  so  that  it  must  be  given  the  desired 
form  by  pouring  when  molten  into  molds.  If  a  malleable  product 


THE  METALLURGY  OF  IRON  AND  STEEL        xiii 

is  desired  the  excess  of  these  constituents  (which  therefore  become 
in  this  sense  impurities)  must  be  removed  by  some  refining  process 
(see  Purification). 

The  production  of  steel  in  two  stages,  i.e.,  first  as  cast  iron  and 
second  by  subsequent  refinement  into  steel,  is  termed  an  indirect 
process  or  method  in  contradistinction  to  the  direct  process  in  which, 
as  described,  the  operation  is  arrested  before  the  iron  has  absorbed 
any  considerable  quantity  of  carbon  and  consequently  is  still 
malleable. 

Purification  usually  consists  in  oxidation  carried  to  the  point 
where  the  impurities  or  excess  constituents  are  nearly  all  removed, 
or  to  the  extent  desired.  As  explained  in  Chemistry,  it  consists 
in  causing  these  ingredients  to  combine  with  oxygen  in  which  con- 
dition they  pass  into  the  slag  if  solid  (or  molten),  or  escape  into 
the  air  if  gaseous. 

The  terms  acid  and  basic,  whether  applied  to  steel  or  a  process, 
refer  to  the  nature  of  the  slag  and  the  corresponding  refining  action 
which  is  occasioned.  Since  the  effect  of  a  given  kind  of  slag  should 
be  confined  to  the  charge,  the  lining  of  the  containing  vessel  or 
furnace  should  be  of  the  same  nature,  to  remain  nearly  unaffected, 
thus  giving  rise  to  acid  (lined)  or  basic  (lined)  vessels  or  furnaces. 

Under  oxidizing  conditions  the  metalloids  such  as  phosphorus 
and  silicon  can  be  eliminated  by  causing  their  oxides  which  are 
acid,  to  combine  with,  and  be  retained  by,  a  base  such  as  lime  if 
this  is  present  in  sufficient  excess.  Sulphur  presents  certain  diffi- 
culties to  removal  under  oxidizing  conditions,  and  the  extent  of  its 
removal  is  usually  erratic.  In  the  elimination  .of  impurities  (basic 
process),  at  a  relatively  low  temperature  phosphorus  and  silicon 
are  acted  upon  and  eliminated  in  preference  to  the  carbon,  but  if 
the  temperature  is  high  the  carbon  is  immediately  affected,  which 
may  result  in  less  perfect  elimination  of  the  first  named. 

Under  strongly  reducing  conditions,  such  as  can  be  secured  in 
the  blast  furnace  or  the  electric  furnace,  the  removal  of  the  sulphur 
is  under  fairly  constant  control;  also  at  very  high  temperatures 
it  is  claimed  that  phosphorus  previously  brought  into  the  slag  by 
oxidizing  conditions  can,  by  powerful  reduction,  as  in  the  electric 
furnace,  be  converted  into  an  even  more  stable  phosphide. 

There  are  two  principal  sources  of  oxygen  (a}  iron  oxide,  and  (/>) 
air,  which  are  used  either  separately  or  in  combination. 

In  puddling  (q.v.)  pig  iron  is  melted  on  the  hearth  of  a  reverbera- 
tory  furnace  (see  Furnace),  in  contact  with  iron  oxide  and  exposed 
to  the  flame;  in  the  charcoal  hearth  processes  (q.v.)  the  pig  iron  is 
exposed  in  a  hearth  to  the  action  of  a  blast  in  conjunction  with  the 
gas  resulting  when  the  fuel  consisting  of  charcoal  is  burned  to 
yield  the  necessary  temperature.  In  both  cases  the  product  be- 
comes pasty  in  its  later  stages  and  contains  an  admixture  of  slag 
most  of  which  is  expelled  by  subsequent  hammering  or  rolling.  The 
open  hearth  process  (q.v.)  is  similar  to  puddling  but,  owing  to  the 
method  of  heating,  the  temperature  is  at  all  stages  maintained  above 
the  melting  point  of  the  metal,  and  hence  the  product  is  fluid  which 
permits  of  a  nearly  complete  separation  from  the  slag.  The  Bes- 


xiv        THE  METALLURGY  OF  IRON  AND  STEEL 

semer  process  (q.v.)  employs  air  alone  which  is  blown  through  the 
molten  metal. 

The  oldest  method  for  producing  steel  in  the  fluid  condition  is 
the  crucible  process  (q.v.)  which  consists  principally  in  the  remelting 
of  suitable  materials,  with  little  if  any  purification  aside  from  the 
elimination  of  oxides. 

The  final  adjustment  of  the  composition  is  described  in  connec- 
tion with  the  various  steel  making  processes,  and  consists  essentially 
in  adding  the  necessary  ingredients  for  this  purpose  and  also  for 
that  of  deoxidation  (see  also  Recarburization). 

The  properties  of  iron  are  chiefly  affected  by  the  carbon  content, 
and  most  of  the  iron  or  steel  of  commerce  contains  this  element  as 
its  principal  constituent,  together  with  varying  amounts  of  man- 
ganese, phosphorus,  sulphur,  and  silicon,  together  with  certain  other 
special  elements,  usually  in  traces,  depending  upon  the  nature  or 
the  source  of  the  ore.  Special  steels  (q.v.)  contain  one  or  more 
special  elements,  such  as  nickel,  chromium,  tungsten,  etc.,  delib- 
erately added  (or  present)  in  amounts  sufficient  to  affect  appreci- 
ably the  physical  properties.  These  serve  both  to  intensify  the 
effect  of  carbon,  as  well  as  to  modify  the  general  or  specific  proper- 
ties, but  without  carbon  their  value  would  be  greatly  diminished. 

It  is  possible  under  the  proper  conditions  to  add  carbon  to 
(carburize)  the  steel  at  temperatures  considerably  below  its  melting 
point,  by  heating  in  intimate  contact  with  carbonaceous  matter, 
and  with  exclusion  of  air  or  other  oxidizing  media.  The  process 
is  relatively  slow  in  comparison  with  treatment  in  the  molten  state, 
the  time  being  roughly  inversely  as  the  temperature.  A  piece 
carburized  only  to  a  slight  depth,  to  produce  better  wearing  prop- 
erties, is  said  to  be  case  hardened.  The  process  may  be  carried 
further  so  that  all  or  nearly  all  the  section  is  affected.  This  subject 
is  discussed  under  Cementation  and  Cementation  Process. 

While  cast  iron  as  such  is  not  usefully  malleable,  and  is  more 
brittle  the  greater  the  proportion  of  carbon  in  the  combined  state, 
it  is  possible  to  restore  this  property  to  a  considerable  degree.  This 
is  accomplished  by  heating  white  iron  (see  Pig  Iron)  castings  in 
contact  with  iron  oxide,  at  a  temperature  below  their  melting  point, 
by  which  means  the  carbon  is  oxidized  or  converted  into  inert 
graphite.  These  are  termed  malleable  castings  (q.v.). 

In  the  case  of  liquid  steel,  after  the  composition  has  been  adjusted 
in  the  furnace  or  the  ladle  into  which  it  is  tapped,  it  is  poured  into 
molds  (see  Casting  and  Molding)  producing  castings  which,  if  to 
be  worked,  are  known  as  ingots.  These  are  then  forged  or  rolled 
to  shape  as  described  under  Forging,  Pressing,  and  Rolling. 

The  chemical  composition  is  determined  by  analytical  methods 
(see  Chemistry)  and  the  physical  properties  (q.v.)  are  checked  by 
some  method  of  testing  (q.v.). 

The  investigation  of  the  nature  of  the  physical  constitution  and 


or!  hn«  ..  1 


THE  METALLURGY  OF  IRON  AND  STEEL         XV 

conditions  which  are  responsible  for  the  physical  properties  shown, 
is  dealt  with  under  Metallography. 

The  structure  may  be  advantageously  or  injuriously  affected  by 
purely  thermal  treatment  (see  Heat  Treatment)  or  by  the  mechan- 
ical working  to  which  it  has  been  subjected  (see  Heat  Treatment 
and  Cold  Working). 

The  joining  together  of  two  pieces,  either  in  a  pasty  condition  or 
by  actual  fusion  commonly  known  as  welding,  is  discussed  under 
that  heading. 

The  causes  for  the  deterioration  or  rusting  of  iron  products, 
whereby  the  metal  tends  to  return  to  its  original  oxidized  state, 
and  the  conditions  or  methods  which  retard  or  overcome  this 
tendency  are  dealt  with  under  Corrosion  and  Protection. 

The  manufacture  of  general  products,  such  as  plates,  shapes  and 
bars,  is  considered  under  Rolling,  while  special  products,  such  as 
sheets  and  tin  plate,  tubes,  and  wire,  are  dealt  with  more  fully 
under  their  respective  headings. 


IRON   AND    STEEL   DEFINITIONS 


A. — (i)  Chemical  symbol  for  argon:  see  page  84;  (2)  critical  point 
of  Tschernoff:  see  page  265;  (3)  for  coating:  see  page  433. 

Ai,A2,Aa.- — Critical  points:  see  page  264. 

Aci,  etc. — Critical  points:  see  page  264. 

AcCTO. — Critical  point:  see  page  264. 

ACTO. — Critical  point:  see  page  264. 

Ae,  Aei,  etc. — Critical  points:  see  page  264. 

Ag. — Chemical  symbol  for  silver  (from  the  Latin  argentum):  see 
page  84. 

Al. — Chemical  symbol  for  aluminum  (q.v.). 

Ar0. — Critical  point:  see  page  264. 

ATI,  etc. — Critical  points:  see  page  264. 

ArCTO. — Critical  point:  see  page  264. 

ArOTC. — Critical  point:  see  page  264. 

As. — Chemical  symbol  for  arsenic :  see  page  84. 

Au. — Chemical  symbol  for  gold  (from  the  Latin  aurum):  sec 
page  84. 

A.  A.  S.  M. — Association  of  American  Steel  Manufacturers. 

A.  B.  M.  A. — American  Boiler  Makers'  Association. 

A.  E.  R.  A. — American  Electric  Railway  Association,  formerly  the 
American  Street  &  Interurban  Electric  Railway  Association. 

A.  E.  R.  E.  A. — American  Electric  Railway  Engineering  Associa- 
tion, one  of  the  subsidiary  associations  of  the  A.  E.  R.  A. 

A.  E.  R.  M.  A. — American  Electric  Railway  Manufacturers'  Asso- 
ciation, one  of  the  subsidiary  associations  of  the  A.  E.  R.  A., 
composed  of  manufacturers  of  electric  railway  supplies. 

A.  F.  A. — American  Foundrymen's  Association. 

A.  I.  M.  E. — American  Institute  of  Mining  Engineers. 

A.  O.  H. — Acid  open  hearth:  see  page  ^3  09. 

A.  R.  A. — American  Railway  Association. 

A.  R.  E.  &  M.  W.  A. — American  Railway  Engineering  &  Mainten- 
ance of  Way  Association;  name  changed  (1911)  to  American 
Railway  Engineering  Association. 

A.  R.  E.  A. — American  Railway  Engineering  Association;  formerly 
the  American  Railway  Engineering  &  Maintenance  of  Way  Asso- 
ciation; one  of  the  subsidiaries  of  the  A.  R.  A. 

A.  R.  M.  M.  A. — American  Railway  Master  Mechanics'  Associa- 
tion; one  of  the  subsidiaries  of  the  A.  R.  A. 

A.  S.  C.  E. — American  Society  of  Civil  Engineers. 

A .  SI  &  I.  E.  R.  A.— American  Street  &  Interurban  Electric  Rail- 
way Association;  name  changed  (1910)  to  A.  E.  R.  A. 

A.  S.  M.  E. — American  Society  of  Mechanical  Engineers. 

A.  S.  T.  M.— American  Society  for  Testing  Materials. 

A.  S.  &  W.  Gage. — American  Steel  &  Wire  Co.'s  Gage;  see  page  188 . 


2  ABEL'S  CARBIDE -ADJUSTABLE  TUYERE 

Abel's  Carbide  of  ITOK. — Cementite:  see  page  272! 

Abrasion. — See  pages  106  and  331. 

Abrasive  Hardness. — See  pages  331  and  478. 

Abscissa. — See  Curve. 

Absolute  Scale. — Of  temperature:  see  page  205. 

Absolute  Strength. — See  page  468. 

Absolute  Temperature. — See  page  205. 

Absolute  Zero. — See  page  205. 

Absolutely  Black  Body. — See  page  207. 

Absorbed  Energy. — See  page  481. 

Absorbens. — See  page  120. 

Absorption. — See  pages  199,  212  and  328. 

Absorption  Point. — See  page  265. 

Absorption  Pyrometer,  Fery. — See  page  207. 

Absorption  Temperature. — See  page  265. 

Absorption  Zone. — See  page  292. 

Accelerated  Corrosion  Test. — See  page  107. 

Accelerated  Stress. — See  page  333. 

Achondrite. — See  page  292. 

Acicular  Crystal. — See  page  126. 

Acicular  Martensite. — See  page  275. 

Acid.— See  page  88. 

Acid  Bessemer  Ore. — See  page  243. 

Acid  Bessemer  Pig. — See  page  343. 

Acid  Bessemer  Process. — See  page  15. 

Acid  Bessemer  Steel. — Steel  made  by  the  acid  Bessemer  process. 

Acid  Bottom. — See  Lining. 

Acid  Brittleness. — See  page  507. 

Acid  Clay. — See  page  396. 

Acid  Converter. — See  page  16. 

Acid  Flux.— See  Flux. 

Acid  Lining. — See  Lining. 

Acid  Open  Hearth  Process. — See  pages  309  and  314. 

Acid  Open  Hearth  Steel. — Steel  made  by  the  acid  open  hearth 

process. 

Acid  Refractories. — See  page  395. 
Acid  Slag.— See  Slag. 
Acid  Theory  of  Corrosion. — See  page  107. 
Acierage. — The  electro-deposition  of  a  thin  layer  of  iron  on  engraved 

copper  plates  to  make  them  more  resistant  to  the  wearing  action 

of  inking  and  printing. 
Acoustic  Signals. — See  page  210. 
Actinometer,  Violle's. — See  page  207. 
Active  Combustion. — See  page  202. 
Adamantine  Silicon. — See  Silicon. 
Adams  Process. — See  page  137. 
Addie  Process. — For  the  recovery  of  tar  and  ammonia  from  the  gas 

of  a  blast  furnace  using  raw  coal. 
Additions. — For  recarburizing :  see  page  393. 
Additional  Strains;  Stresses. — See  page  332. 
Additive  Property. — See  page  337. 
Adjustable  Tuyere. — See  page  182. 


ADJUSTING  PROCESS— AIRED  BARS  3 

Adjusting  Process  (Howe).— One  in  which  the  composition  is 
determined  and  arranged. 

Adsorption. — See  page  328. 

Adsorption  Theory. — Of  passivity:  see  page  364. 

Advance  Alloy. — For  thermo-couples:  see  page  209. 

Aeolic. — See  page  270. 

Aeolic  Steel. — See  page  273. 

Aeoliochronous. — Or  Aeoliotachic ;  suggested  by  Howe  to  express 
the  fact  that  cooling  and  contraction,  even  if  equal  in  amount, 
occur  at  different  rates  in  different  portions  of  a  piece. 

Aeoliotachic. — See  Aeoliochronous. 

Aeolotropic. — See  page  330. 

Aerolite. — See  page  290. 

Aerolitics. — See  page  291. 

Aerosiderite. — See  page  291. 

Aerosiderolite. — See  page  291. 

Affinity.— See  page  84. 

After  Blow. — See  page  21. 

After  Glow  (rare). — Recalescence :  see  page  265. 

Aggregate. — See  page  264. 

Aging.— See  page  333. 

Agglomeration. — See  page  81. 

Aggregation,  State  of. — See  page  81. 

Agitator,  Allen's. — See  page  62. 

Agraphitic  Carbon. — See  pages  50  and  278. 

Air  Belt— See  page  182. 

Air  Box. — See  page  17. 

Air  Casing. — A  casing  enclosing  air  to  prevent  or  reduce  loss  of  heat 
by  radiation. 

Air  Chamber. — See  page  182. 

Air  Channels. — Flues  under  the  hearth  and  the  fire-bridge  of  a 
reverberatory  furnace  to  keep  them  cool. 

Air  Cooling. — See  pages  227  and  232. 

Air-dilution  Pyrometer. — See  page  210. 

Air  Dry. — Dried  by  simple  exposure  to  the  air,  without  the  appli- 
cation of  heat. 

Air  Furnace. — See  page  182. 

Air  Gas.— See  Oil  Gas. 

Air  Hardening. — See  page  227. 

Air-hardening  Steel. — See  page  445. 

Ah*  Heating. — Heating  in  air. 

Air  Pits  (Ewing  and  Rosenhain). — An  epithet  applied  to  micro- 
scopic air  bubbles,  which  have  taken  a  geometrical  form,  found  on 
the  surface  of  certain  metals  cast  on  glass. 

Air  Pyrometer. — See  page  205. 

Air-quenched  Steel. — See  page  445. 

Air  Quenching. — See  page  227. 

Air  Refining  Process. — Bessemer  Process,  q.v. 

Air  Thermometer. — See  page  205. 

Air  Tinting.— See  page  288. 

Air  Toughening. — See  page  232. 

Aired  Bars. — See  page  71. 


4  AKERMAN'S  THEORY— ALLOY 

Akennan's  Theory. — Of  hardening :  see  page  280. 

Alexander  and  M'Cosh  Process. — For  the  recovery  of  tar  and  am- 
monia from  the  gas  of  a  blast  furnace  using  raw  coal. 

All-mine  Pig. — See  page  350. 

Allen's  Agitator. — See  page  62. 

Allevard  Process. — See  page  154. 

Alligator  Cracks. — See  page  112. 

Alligator  Scale. — A  heavy,  very  infusible  scale  formed  during  the 
reheating  of  chrome  steel. 

Alligator  Shears. — See  Shears. 

Alligator  Squeezer. — See  page  377. 

Alling's  Test. — See  page  216. 

Allis-Andrew  Process. — See  page  416. 

Allomorph. — See  page  122. 

Allotrimorphic  Crystal. — See  page  122. 

Allotropic  Modifications. — Of  iron:  see  page  264. 

Allotropic  Theory. — Of  hardening:  see  page  279. 

Allotropic  Transformation. — See  page  327. 

Allotropy. — A  change  in  the  properties  of  an  element  without  change 
of  state.  It  is  habitually  accompanied  by  a  change  of  internal 
energy.  It  is  due  in  some,  and  perhaps  in  all,  cases  to  a 
change  in  the  number  or  in  the  arrangement  of  the  atoms  in  the 
molecule  (Howe).  Allotropic  varieties  are  sometimes  termed 
isomerides. 

Alloy. — A  union,  possessing  metallic  properties,  of  two  or  more 
metallic  elements,  or  of  metallic  elements  and  metalloids,  which 
are  miscible  with  each  other,  at  least  to  a  certain  extent,  when  mol- 
ten to  form  a  homogeneous  liquid,  and  do  not  separate  into  dis- 
tinct layers  when  solid.  Such  combinations  when  cold  may  con- 
sist of  mechanical  mixtures,  eutectics  or  eutectoids,  solid  solu- 
tions, or  chemical  compounds,  one  or  more  of  which  may  exist 
at  the  same  time.  Amalgamation  is  the  alloying  of  mercury  with 
some  other  metal  yielding  (at  least  temporarily)  a  plastic  or  liquid 
mass;  the  term  is  sometimes  used  improperly,  where  mercury  is 
absent,  in  the  ordinary  sense  of  alloying.  When  composed  of 
two  or  more  elements  they  are  termed  respectively  binary,  ter- 
nary, quarternary  alloys,  etc.  An  alloy,  composed  of  metallic 
elements  only,  is  sometimes  referred  to  as  a  metallic,  intermetal- 
lic,  or  simple  alloy ;  where  a  definite  chemical  compound  exists,  it 
may  be  termed  an  intermetallic  compound  or  definite  alloy;  a 
mixture  of  the  two,  a  metallo-metallic  compound;  a  eutectomeric 
alloy  is  one  which,  in  one  proportion  of  its  constituents,  forms  a 
eutectic.  The  dominant  metal  or  element  is  one  which  princi- 
pally affects  the  properties.  Alloys  may  be  divided  into  ferrous 
and  non-ferrous  depending  on  whether  or  not  iron  is  the  dominant 
element.  They  may  also  be  classified  as  heavy,  where  they  con- 
tain principally  metals  such  as  iron,  nickel,  or  copper  with  a 
specific  gravity  over  about  7;  and  light,  with,metals  with  a  specific 
gravity  less  than  this.  Fusible  alloys  are  those  which  melt  at  a 
very  low  temperature,  e.g.,  Wood's  fusible  alloy  which  melts  at 
65°  C.  (149°  F.) ;  they  usually  consist  of  bismuth,  lead  and  tin  in 
various  proportions,  and  iron  only  as  an  impurity.  Magnetic 


ALLOY  5 

alloys  (generally  referred  to  as  Heussler's  alloys)  do  not  contain 
iron  but  consist  of  metals  which,  separately,  are  non-magnetic  or 
only  slightly  so;'  the  composition  may  be  taken  as  approximately 
copper  60,  manganese  20,  aluminum  14.  Overbeck  suggested 
the  term  metamagnetic  alloys  for  those  which  are  paramagnetic 
or  diamagnetic,  according  to  the  strength  of  the  magnetic  field — 
the  case  of  some  alloys  of  copper  and  zinc.  Hannover's  process 
for  making  metallic  sponges  consists  in  heating  a  eutectic  alloy 
to  a  temperature  within  its  freezing  range  (see  Metallography, 
page  267)  and  centrifuging  it,  whereby  the  molten  portion  is 
expelled.  What  is  known  as  the  superposing  method  of  forming 
alloys  consists  in  first  melting  the  metal  of  highest  specific  gravity 
and  then  pouring  on  top  of  this,  in  a  molten  condition,  the  other 
and  lighter  metal.  The  two  metals  will  alloy  in  such  a  way  that 
a  vertical  cross  section  will  show  crystals  of  a  pure  metal  at  one 
end  and  crystals  of  the  other  metal  at  the  other  end,  while  be- 
tween these  the  metals  will  be  found  alloyed  in  all  possible  pro- 
portions (Metallographist,  1902,  247).  (For  further  details  of 
the  constitution  and  properties  of  alloys  see  the  treatises  on  the 
subject  by  Howe,  Sauveur,  Desch,  Heyn,  Rosenhain,  Guertler, 
etc.,  also  Metallography). 

Alloy  Cast  Iron. — See  page  351. 

Alloy  Element. — See  pages  351  and  443. 

Alloy  Steels. — See  page  443. 

Alloyed  Carbon  Iron. — See  page  443. 

Almond  Furnace. — A  remelting  or  refining  furnace  of  the  reverbera- 
tory  type;  name  derived  from  allemand  (German). 

Alpha  Cementite; — See  page  273. 

Alpha  (a)  Iron. — See  pages  264  and  272. 

Alpha  Iron  Theory;  Alpha  Theory. — Of  hardening:  see  page  280. 

Altar. — Of  a  furnace:  see  pages  183  and  375. 

Altered  Iron. — See  page  364. 

Alternate  Stresses. — See  page  333. 

Alumaloyd. — See  page  372. 

Aluminium  (Eng.). — See  Aluminum. 

Alumino-ferrite. — See  page  272.     f 

Alumino -thermic  Process. — Carried  out  by  means  of  the  heat 
developed  by  the  burning  (oxidation)  of  metallic  aluminum;  see 
Goldschmidt  process-  and  Rossi  process. 

Aluminous  Clay. — See  page  396. 

Aluminum. — Al;  at.  wt,  27;  melt,  pt.,  625°  C.  (1157°  F.);  sp.  gr., 
2.58  (by  hammering  or  rolling  this  may  be  raised  to  2.68).  A 
white  metal,  with  high  tensile  strength,  malleability,  and  con- 
ductivity. Its  principal  application  in  the  manufacture  of  steel  is 
as  a  deoxidizer,  for  which  purpose  it  is  usually  added  (up  to  about 
3  or  4  oz.  per  ton)  in  the  mold  during  pouring.  It  is  used  as  the 
pure  metal,  or  as  an  alloy  with  iron  called  ferro-aluminum  (see 
page  351),  and  is  rarely  a  constituent/)  f  steel  (see  page  453). 

Aluminum  Coating. — See  page  372. 

Aluminum  Steels. — See  page  453. 

Alundum. — A  trade  name  for  an  abrasive  consisting  of  fused  alu- 
mina, produced  in  the  electric  furnace. 


6  AMALGAMATION— ANNEALING  CHARGE 

Amalgamation. — See  Alloy. 

American  Bloomary  Process. — See  page  137. 

American  Charcoal  Irons. — See  page  350. 

American  Forge. — See  page  137. 

American  Forge  and  Foundry  Iron. — Graded  by  analysis:  see  page 
348;  graded  by  fracture;  see  page  347. 

American  Lancashire  Process. — See  page  77. 

American  Process. — For  malleable  castings:  see  page  258. 

American  Steel  &  Wire  Co.'s  Gage.— See  page  188. 

American  Wire  Gage. — See  page  188. 

Amet-Ensign  Oil  Gas  Producer.— See  Oil  Gas. 

Amianthus. — See  Salamander. 

Amorphizing. — See  page  282. 

Amorphous. — See  page  119. 

Amorphous  Antimony. — See  Antimony. 

Amorphous  Boron. — See  Boron. 

Amorphous  Carbon. — See  Carbon. 

Amorphous  Cement  Theory. — See  page  281. 

Amorphous  Fracture. — See  page  178. 

Amorphous  Iron  Theory. — Of  hardening:  see  page  281. 

Amorphous  Phase. — See  page  281. 

Amorphous  Silicon. — See  Silicon. 

Amorphous  State. — See  page  281. 

Amorphous  Sulphur. — See  Sulphur. 

Amorphous  Theory. — Of  hardening:  see  page  281. 

Amorphous  Tin.— See  Tin. 

Amount  of  Heat. — See  page  199. 

Amsler-Laff on  Test. — (i)  Hardness  test:  see  page  47 8;  (2)  vibratory 
test:  see  page  482. 

Analysis;  analytic  (al)  Chemistry. — See  page  82. 

Analytical  Reaction. — See  page  87. 

Anchor  Bolt. — In  molding:  see  page  299. 

Ancony  (obs.). — See  page  135. 

Anderson  Furnace. — See  page  154. 

Angle  of  Contact. — In  rolling:  see  page  407. 

Angular  Fracture. — See  page  179. 

Angular  Method  of  Rolling. — See  page  420. 

Anhedrpn. — See  page  122. 

Anhydride. — See  page  88. 

Anion. — See  page  89. 

Anion  Discharge  Theory. — Of  passivity:  see  page  364. 

Anisometric  System. — Of  crystallization:  see  page  120. 

Anisotropic ;  Anisotropy. — See  page  330. 

Ankerite. — A  crystallized  variety  of  dolomite  containing  a  large  pro- 
portion of  iron. 

Ankony  (obs.). — Double  gross  ton  of  2464  pounds. 

Annealing. — (i)  Of  crucibles:  see  page  112;  (2)  of  steel  or  iron: 
page  231;  -(3)  of  malleable  castings:  see  page  258;  (4)  of  sheets: 
see  page  431;  (s)  of  tubes:  see  page  492. 

Annealing  Box. — See  page  431. 

Annealing  Carbon. — See  pages  257  and  278. 

Annealing  Charge. — See  page  233. 


ANNEALING  FURNACE— ARC-RESISTANCE  FURNACE  7 

Annealing  Furnace. — A  type  of  furnace  used  for  annealing,  i.e., 
heating  to  a  low  temperature:  see  Furnace. 

Annealing  Oven. — For  crucibles:  see  page  112. 

Annealing  Pit. — A  pit,  generally  lined  with  brick,  in  which  castings, 
particularly  cast-iron  car  wheels,  are  allowed  to  cool  slowly. 

Annealing  Pot. — See  pages  258  and  431. 

Annealing  Temperature. — The  temperature  to  which  material  is 
heated  for  annealing. 

Annealing  Twin. — See  page  125. 

Anode. — See  page  89. 

Anodic  Passivity. — See  page  364. 

Anodic  Polarization. — See  page  364. 

Anorthic  System. — Of  crystallization:  see  page  120. 

Ansaldo  Process. — See  page  60. 

Anthracite ;  anthracite  coal. — See  Coal. 

Anthracite  Coal  Apples. — See  Coal. 

Anthracite  Furnace. — Kind  of  blast  furnace :  see  page  39. 

Anthracite  Pig.— See  page  343- 

Anthracitic  Coal.— See  Coal. 

Anti-cement. — In  cementation:  see  pa'ge  70. 

Anti -fatigue  Steel. — See  page  452. 

Anti-friction  Metal. — A  bearing  metal,  such  as  babbitt,  used  to  re- 
duce the  friction  of  bearings.  It  usually  consists  of  various  pro- 
portions of  lead,  tin,  zinc,  and  antimony. 

Antimony.— Sb;  at.  wt,  120;  melt,  pt,  630°  C.  (1166°  F.);  sp.  gr.f 
crystalline,  6.7  to  6.8,  amorphous,  5.78.  It  is  found  in  the  free 
state,  but  its  most  important  occurrence  is  in  combination  with 
other  elements.  When  pure  it  is  a  white  brittle  metal.  It  is  not 
of  value  as  a  constituent  of  steel,  as  it  is  generally  considered  that 
even  very  small  percentages  render  it  both  hot  and  cold  short. 
Metallic  antimony  as  found  on  the  market  is  sometimes  known  as 
French  metal. 

Anti-piping  Thermit. — See  page  61. 

Anvil;  Anvil  Block. — See  Hammer. 

Anvil  Effect. — The  effect  on  rails  due  to  pounding  of  flat  wheels  and 
lack  of  counterbalance  of  driving  wheels.  Especially  pronounced 
when  the  track  is  frozen.  The  road  bed  is  considered  as  forming 
the  anvil,  on  which  the  rails  receive  the  hammer-like  blows  of  the 
wheels. 

Aphanitic  Fracture. — See  page  178. 

Apparent  Elastic  Limit. — See  page  470. 

Apparent  Stress. — See  page  332. 

Apple.  Coal.— See  Coal. 

Applied  Chemistry. — See  page  81. 

Aproning. — In  puddling:  see  page  377. 

Aqua  Regia.— See  page  84. 

Aqueo-igneous  Fusion;  Aqueous  Fusion. — See  page  201. 

Arbitration  Bar. — See  page  484. 

Arborescent  Crystal. — See  pages  55. 

Arc  Furnace;  Heating. — See  page  153. 

Arc  Radiation  Furnace. — See  page  153. 

Arc-resistance  Furnace. — See  page  153. 


8  ARC  WELDING— ARMOR  PLATE 

Arc  Welding. — See  page  503. 

Argillaceous. — Containing  or  consisting  of  clay. 

Argillaceous  Iron  Ore;  Siderite. — See  page  244. 

Armco  Iron. — The  trade  name  for  so-called  "ingot  iron,"  extremely 
low  in  carbon  and  other  elements,  produced  by  a  special  open 
hearth  process. 

Armor  Plate. — Special,  usually  heavy,  iron  plates,  forming  a  pro- 
tective sheathing  for  war  vessels  and  also  for  certain  types  of  land 
fortifications,  designed  to  withstand  the  penetration  of  projectiles. 
Much  lighter  plates,  sometimes  less  than  one-quarter  inch  thick, 
have  recently  been  developed  for  the  protection  of  motor  cars, 
railway  trains,  etc.  At  first  it  was  made  of  cast  iron,  or  of  un- 
treated wrought  iron;  later,  of  alternate  layers  of  steel  and 
wrought  iron,  cast  or  welded  together  (compound  armor  plate,  or 
steel-faced  wrought -iron  armor  plate),  the  steel  to  give  hardness, 
and  the  wrought  iron  toughness.  It  is  at  present  made  exclu- 
sively of  steel  (usually  special  steel),  one  face  of  which  is  car- 
burized  (by  heating  in  contact  with  carbonaceous  matter  at  a  high 
temperature)  and  hardened  to  a  depth  of  about  an  inch,  the  car- 
burizing  effect  decreasing  with  the  depth  below  the  surface,  the  rest 
of  the  plate  being  comparatively  soft  (low  in  carbon)  and  tough; 
this  is  called  face-hardened  armor  plate  or  cemented  armor  plate. 
The  De  Marre  formula  gives  the  striking  velocity  necessary  to 
effect  complete  penetration  of  homogeneous  nickel  steel  (not 
carburized  on  one  face  but  of  uniform  composition  and  structure 
throughout);  it  is  as  follows: 

T_       ,             ,  0.75^  X  0.70 
V  =  (3.00945) -^- 

V  =  striking  velocity  in  foot  pounds; 
d  =  caliber  of  gun  in  inches; 
e  =  thickness  of  plate  in  inches; 
p  —  weight  of  projectile  in  pounds. 

A  correction  of  the  velocity  thus  calculated  must  be  made, 
depending  upon  the  size  of  gun  and  thickness  or  type  of  plate. 
The  penetration  of  a  given  projectile,  with  corresponding  resist- 
ance offered  by  the  plate,  based  on  this  formula,  is  known  as  the 
figure  of  merit. 

The  Beardmore  process  consists  in  casting  alternate  layers  of 
hard  and  soft  steel.  This  material  is  then  rolled  or  forged, 
hardened,  etc. 

Bessemer's  process  for  armor  plate  consisted  in  piling  alter- 
nately plates  of  cast  (crucible)  steel  on  plates  of  puddled  or  scrap 
iron  which  were  first  carefully  cleaned,  and  then  coated  with  a 
very  fusible  flux.  The  pile  was  then  welded  together,  etc. 

The  Corey  reforging  process  consisted  in  forging  nearly  to 
size,  then  carburizing  and  forging  down  to  exact  size,  followed  by 
hardening. 

In  the  Demenge  process  for  face  hardening,  one  side  of  the  mold 
is  lined  with  carbonaceous  material,  to  be  later  taken  up  by  the 
steel,  and  the  opposite  side  is  formed  as  a  chill,  consisting  of  a 
mass  of  iron  through  which  water  may  be  circulated. 


ARMOR  PLATE— ARRESTED  PURIFICATION         9 

The  Ellis  process  for  making  compound  armor  consisted  in 
fastening  a  hard  steel  and  a  soft  iron  plate  together  by  pouring 
molten  steel  between. 

Gruson's  chilled  cast-iron  armor  was  made  by  pouring  cast 
iron  in  chill  (iron)  molds. 

Thomas  Hampton's  process  consisted  in  taking  steel  plates 
or  slabs  which  were  piled,  reheated,  and  rolled  or  hammered 
together,  then  carburized  on  one  face,  and  afterward  rerolled, 
if  desired,  and  hardened. 

The  Harvey  process  consists  in  impregnating  one  face  of  a  soft 
steel  plate,  which  has  been  rolled  or  forged  down,  with  carbon  by 
heating  it  for  a  number  of  days  at  a  temperature  sufficient  to  melt 
certain  grades  of  cast  iron  (say,  1200°  C.;  2192°  F.)  in  contact  with 
carbonaceous  material,  after  which  the  carburized  face  is  hard- 
ened by  spraying  it  with  cold  water.  This  method  of  heating  is 
sometimes  referred  to  as  decremental  hardening,  since  the  carbon 
(and  with  it  the  hardness)  decreases  below  the  carburized 
surface. 

The  Krupp  process  is  very  similar  to  the  Harvey,  one  patent 
specifying  heating  the  plate  with  the  surface  to  be  carburized  in 
contact  with  illuminating  gas  which  deposits  a  layer  of  fine  carbon 
which  is  readily  taken  up  by  the  steel;  another  has  to  do  with 
producing  a  fibrous  structure  by  making  the  steel  of  special  com- 
position, and  by  heating  it  to  a  certain  temperature.  The  prod- 
uct is  sometimes  called  Krupp  cemented  armor  (K.  C.  armor). 

The  St.  Chamond  armor  plate  consists  of  steel  containing  nickel 
and  chromium  in  addition  to  carbon. 

The  Tressider  process  for  hardening  armor  plate  consists  in 
subjecting  one  or  both  faces  to  a  spray  of  cold  liquid  supplied 
under  considerable  pressure  by  a  great  number  of  smalt  jets. 

Whitworth  armor  plate  was  made  of  fluid  compressed  steel  built 
up  in  hexagonal  sections,  each  of  which  was  composed  of  con- 
centric rings  around  a  central  circular  disk,  the  object  being  to 
eliminate  the  liability  of  cracking,  or  to  restrict  its  area. 

The  Wilson  process  for  making  compound  armor  plate  con- 
sisted in  pouring  molten  steel  on  a  soft  iron  plate,  in  the  ratio  of 
one-third  steel  to  two-thirds  iron.  The  resulting  ingot  was  then 
heated,  rolled,  and  machined.  This  is  an  improvement  of  Cam- 
mel's  method. 

See  also  Casting  for  certain  other  methods  similar  to  those 
described  above. 

Armored. — A  term  sometimes  used  for  case-hardened:  see  page 
67. 

Armored  Glass.— See  Wire  Glass. 

Armorized. — A    term    sometimes    used    for    case-hardened:    see 
page  67. 

Arnold's  Subcarbide  Theory.— Of  hardening:  see  page  280. 

Arnold  Test— See  page  482. 

Arnoldite:  Arnpldite  Steels. — See  page  277. 

Arrestation  Point. — See  page  264. 

Arrested  Purification. — Not  carried  to  its  greatest  possible  extent, 
as  in  pig  washing. 


io  ARRHENIUS'     THEORY— AUTOMORPHIC     CRYSTAL 

Arrhenius'  Theory. — See  page  89. 

Arris. — The  rough  edge  resulting  from  the  cold  shearing  of  plates, 

etc. 

Arsenide  Ore. — See  page  244. 
Arsenppyrite. — See  page  245. 
Artificial  Steel. — See  page  71. 
Ascensional  Casting. — See  page  57. 

Ash;  Ashes. — In  its  chemical  sense  ash  is  the  incombustible  residue 
of  a  substance;  ashes,  and  sometimes  ash,  is  used  for  that  portion 
of  a  fuel  which  has  not  burned,  but  which  may  contain  a  small 
proportion  of  combustible  matter. 
Asiderite. — See  page  291. 
Assaying. — See  page  82. 
Association. — See  page  84. 
Assorting  Room. — See  page  433. 
Astrolitholpgy. — See  page  291. 

Asymmetric  System. — Of  crystallization:  see  page  120. 
Ataxite. — See  page  292. 
-ate.: — Chemical  suffix:  see  page  88. 

Atmosphere. — (i)  The  gaseous  envelope  surrounding  the  earth;  (2) 
the  pressure  of  the  air  at  the  surface  of  the  earth,  generally  con- 
sidered as  14.7  pounds  to  the  square  inch,  with  the  barometer 
at  30"  (760  millimeters) :  commonly  used  as  a  unit  for  expressing 
gas  pressures. 

Atom. — See  page  81. 

Atom,  per  cent.— See  page  83. 

Atomic  Aggregate. — See  page  81. 

Atomic  Heat. — See  page  85. 

Atomic  Theory. — See  page  81. 

Atomic  Volume. — See  page  87. 

Atomic  Weight. — See  page  83. 

Atomicity.— See  page  86. 

Attack. — Form  of  testing:  see  page  482. 

Attack-polishing.— See  page  288. 

Attrition. — See  page  331. 

Atwood  Process. — See  page  117. 

Aubertin  and  Boblique  Process. — See  page  384. 

Auchy's  Chemical  Theory.— Of  iron-carbon  steels:  see  page  278. 

Austenite. — See  page  274. 

Austenite-pearlite  Inversion. — See  page  275. 

Austenite  Range. — See  page  275. 

Austenite  Steels. — See  page  276. 

Austenitic  Manganese  Steel. — See  page  451. 

Austenitic  Steels. — See  page  445. 

Austenpid.— See  page  275. 

Austenito-martensitic  Steel. — See  page  276. 

Autoclave. — See  Slag  Cement. 

Autoelectrolysis. — See  page  108. 

Autogenous  Electrolysis. — See  page  108. 

Autogenous  Soldering,  Welding. — See  page  505. 

Autographic  Recorder. — In  testing:  see  page  471. 

Automorphic  Crystal. — See  page  122. 


AUTOREDUCTION— AXIS  OF  PRINCIPAL  STRESS   II 

Autoreduction. — Of  certain  compounds  which  can  be  reduced  to  the 

metallic  condition  by  the  simple  application  of  heat. 
Avogadro's  Law. — See  page  85. 
Axe  Temper. — See  Temper. 
Axial  Forces;  Load. — See  page  332. 
Axial  Segregate. — See  page  56. 
Axial  Stresses. — See  page  332. 
Axis. — See  Curve. 
Axis  of  Principal  Stress. — See  page  332. 


B 

B. — (i)  Chemical  symbol  for  boron,  q.v.;  (2)  grade  of  wrought  iron, 
also  of  wire:  see  page  509. 

Ba. — Chemical  symbol  for  barium:  see  page  84. 

Be. — Chemical  symbol  for  beryllium  (now  called  glucinium) :  see 
page  84. 

Bi. — Chemical  symbol  for  bismuth;  see  page  84. 

Br. — Chemical  symbol  for  bromine:  see  page  84. 

B.  G.  (Eng.). — Sheet  and  hoop  iron  standard  gage. 

B.  H. ;  B.  B.  H. — Best  hammered;  best  best  hammered ;  trade  desig- 
nations for  qualities  of  hammered  wrought  iron. 

B.  O.  H. — Basic  open  hearth:  see  page  309. 

B.  O.  V. — Brown  oil  of  vitriol:  sp.  gr.,  1.6  to  1.74. 

B.  &.  S.  Gage. — Brown  &  Sharpe  gage:  see  page  188. 

B.  T.  U. — British  thermal  unit:  see  page  199. 

B.  W.  G. — Birmingham  wire  gage:  see  page  188.       « 

Baby  Bessemer  Converter. — See  page  23. 

Bacillar  Structure. — See  page  125. 

Back. — Of  a  converter:  see  page  18. 

Bacon  and  Thomas  Process. — See  page  384. 

Bailey  Resistance  Furnace. — See  page  154. 

Bajault  and  Roche  Process. — See  page  113. 

Baked. — (i)  Of  steel:  see  page  226;  (2)  of  wire:  see  page  507. 

Baker. — For  wire:  see  page  507. 

Baker  Process. — See  page  384. 

Balanced  Roll.— See  page  406. 

Ball. — (i)  In  puddling:  see  page  376;  (2)  in  making  welded  tubes: 
see  page  490. 

Ball  Mill. — A  mill  for  grinding  materials  into  a  very  fine  powder, 
consisting  of  a  revolving  cylinder  in  which  are  heavy  stone  or 
iron  balls. 

Ball  Stuff. — See  pages  17  and  396. 

Ball  Test. — For  hardness:  see  page  477. 

Ball  and  Wingham  Process. — See  page  384. 

Ballantine  Method. — For  determining  hardness:  see  page  478. 

Bailer. — See  page  21. 

Balling  Furnace. — See  page  377. 

Balling -heat  Processes. — See  page  134. 

Ballistic  Test. — See  page  482. 

Balthasar  Mill. — See  page  417. 

Banal  Deformation. — See  page  126. 

Banded  Structure. — See  page  127. 

Bank. — (i)A  row  of  soaking  pits  having  the  same  set  of  regenera- 
tors; (2)  to  shut  down  a  blast  furnace  temporarily  by  cutting  off 
.the  blast:  see  page  37;  (3)  a  rack  or  place  where  rolled  material  is 
piled  to  cool  (Eng.). 

Bank  Oven. — See  page  95. 

Bar.— See  oag.e  468. 


BAR  IRON— BATHO  FURNACE  13 

Bar  Iron. — Wrought  iron  in  the  form  of  bars. 

Bar  Mill. — See  pages  413. 

Bar  Steel. — See  page  71. 

Barba's  Law. — See  page  473. 

Barff  Process;  Barffed. — See  page  367. 

Bark. — Of  steel:  see  page  226. 

Bark  Mill. — A  mill  for  crushing  the  graphite  used  in  the  manufac- 
ture of  graphite  crucibles. 

Barked  Fracture. — See  page  178. 

Barnett  Process. — See  page  379- 

Barrel. — Of  a  roll:  see  page  403. 

Barrow  Charging. — See  page  33. 

Barus  Gas  Pyrometer. — See  page  207. 

Barus  Thermoelectric  Pyrometer. — See  page  208. 

Basal  Cleavage. — See  page  124. 

Base. — (i)  In  chemistry:  see  page  88;  (2)  ground  mass:  see  page 
125;  (3)  of  a  paint:  see  page  365. 

Base  Box. — Of  tin  plate:  see  page  433. 

Base  Material. — Of  enamels:  see  page  370. 

Base  Metal. — See  page  84. 

Base -metal  Couples. — See  page  209. 

Basic  Bessemer  Ore. — See  page  243. 
.Basic  Bessemer  Pig. — See  page  343. 

Basic  Bessemer  Process. — See  page  15. 

Basic  Bessemer  Steel. — Steel  made  by  the  basic  Bessemer  process. 

Basic  Bottom. — See  Lining. 

Basic  Clay — See  page  396. 

Basic  Converter. — See  page  17. 

Basic  Crucible  Process. — See  page  113. 

Basic  Flux.— See  Flux. 

Basic  Iron. — See  page  343. 

Basic  Lining. — See  Lining. 

Basic  Material. — See  page  17. 

Basic  Open  Hearth  Process. — See  pages  309  and  315. 

Basic  Open  Hearth  Steel. — Steel  made  by  the  basic  open  hearth 
process. 

Basic  Pig  Iron.— See  pages  343  and  346. 

Basic  Purifying  Processes. — See  page  382. 

Basic  Refractories. — See  page  396. 

Basic  Slag.— See  Slag. 

Basicity. — See  page  87. 

Basin. — In  puddling:  see  page  374. 

Bastard  Slag.— See  Slag. 

Bat-Stick. — A  stick — usually  a  sledge  handle — used  by  a  hammer- 
man for  the  purpose  of  revolving  the  axle  or  forging  on  which  he 
may  be  working.  Usually  the  forging  is  hanging  in  a  sling,  sup- 
ported by  a  chain  pulley.  The  hammerman  slips  his  bat-stick 
between  the  reins  of  the  tongs  next  the  jaws  and  uses  it  as  a  lever 
to  turn  the  forging  after  each  blow  of  the  hammer  (G.  Aertsen). 

Batch. — In  making  crucibles:  see  page  112. 

Bates  Process. — See  page  68. 

Batho  Furnace. — See  page  312. 


14  BATTED— BENDING  MOMENT 

Batted. — Of  wire:  see  page  508. 

Battery. — See  Hammer. 

Battetura  (Eng.). — Hammer  scale. 

Bauernofen. — See  page  147. 

Baumann's  Method.— For  sulphur  prints:  see  page  288. 

Baur  Method. — For  determining  hardness:  see  page  480. 

Bauschinger's  Formula. — For  tensile  strength:  see  page  337. 

Bauxite ;  Bauxite  Brick. — See  page  398. 

Baykoff's  Method. — For  hot  etching:  see  page  287. 

Bead. — Or  blister:  see  page  71. 

Beaded  Pearlite.— See  page  274. 

Beading.— Of  boiler  tubes;  rounding  off  the  ends  after  expanding, 

or  the  ends  so  rounded  off. 
Beam. — Of  a  testng  machine:  see  page  469. 
Bean  Ore. — See  page  244. 
Bear. — See  Salamander. 

Beardmore  and  Cherrie  Process.— See  page  60. 
Beardmore  Process. — See  page  8. 
Bearing  Compression. — See  page  336. 

Bearing  Metal. — Used  for  bearings :  same  as  Anti-friction  Metal. 
Beasley  Process. — See  page  379. 
Beaumontague  (Eng.). — A  compound  used  for  filling  up  holes  in 

castings,  etc.,  for  the  purpose  of  concealment. 
Becquerel  Effect. — See  page  209. 
Becquerel  Gas  Pyrometer.— See  page  207. 
Becquerel  Optical  Pyrometer.— See  page  207. 
Becquerel  Thermoelectric  Pyrometer.— See  page  208. 
Bed. — (i)  Layer,  e.g.,  a  bed  of  coal;  (2)  bottom  of  a  furnace,  etc. 
Bedson  Continuous  Galvanizing  Process.— See  pages  370  and  509. 
Bedson  Mill. — See  page  412. 
Beehive  Coke;  Oven. — See  page  95. 
Beetle. — Or  maul:  a  heavy  wooden  mallet. 
Behrens  Scale.— Of  hardness:  see  page  480. 
Beilby's  Amorphous  Cement;  Amorphous  Phase:  see  page  281. 
Beilby's  Hard  Iron. — See  page  281. 
Beilby's  Theory. — Of  hardening:  see  page  281. 
Belford  Process. — See  page  137. 
Belgian  Mill.— See  page  416. 
Bell—  (i)  Of  a  blast  furnace:  see  page  32;  (2)  in  the  manufacture 

of  tubes:  see  page  489. 
Bell  and  Hopper. — See  page  32. 
Bell-Krupp  Pig  Washing  Process.— See  page  383. 
Bell  Process. — (i)  Of  dephosphorizing  or  pig  washing:  See  page 

383;  (2)  for  purification:  see  page  384. 
Bellied  (Belly)  Core.— See  page  299. 
Bellied  (Belly)  Bass. — See  page  405. 
Belly. — Of  a  converter:  see  page  17. 
Belly  Helve. — See  Hammer. 
Belly  Walls.— Of  a  blast  furnace:  see  page  27. 
Belt  Driven. — See  page  407. 
Bench  Hardened  Wire. — See  page  508. 
Bend  (Bending)  Test. — See  page  476. 
Bending  Moment. — See  page  337. 


BENDING  RESILIENCE— BESSEMER  PROCESS      15 

Bending  Resilience. — See  page  331. 

Bending  Rolls. — Heavy  rolls  of  cast  iron  or  steel,  set  in  strong  hous- 
ings, and  used  either  for  the  straightening  of  crooked  plates,  or- for 
bending  them  into  arcs  of  circles  or  into  complete  cylinders. 

Bending  Strength. — See  page  330. 

Benedicks'  Colloid  Hypothesis. — Of  osmondite:  see  page  277. 

Benedicks'  Equilibrium  Diagram. — See  page  271. 

Benedicks'  Formula. — For  Brinell  hardness  number:  see  page  478. 

Benedicks'  Reagent. — See  page  .287 

Benedicks'  Theory. — Of  beta  iron:  see  page  280. 

Benefaction ;  Beneficiation. — See  Ore. 

Benmutic. — See  page  270. 

Benmutic  Steel. — See  page  273. 

Berard  Process.— See  page  317. 

Bernardos  Process. — See  page  503. 

Berner  Process. — See  page  137. 

Berthelot  Calorimeter. — See  page  201. 

Bertrand  Process. — See  page  368. 

Bertrand-Thiel  Process. — See  page  315. 

Bessemer  Ferro -silicon. — See  page  354. 

Bessemer  Iron;  Metal;  Pig. — See  page  343. 

Bessemer  Ore. — See  page  243. 

Bessemer  (Anthony)  Process. — Consisted  in  exposing  molten  pig 
iron  to  the  action  of  air,  steam,  or  even  pureoxygen  in  a  cylindrical, 
revolving  reverberatory  furnace. 

Bessemer  (Henry)  Process. — (i)  For  armor  plate:  see  page  8;  (2) 
for  fluid  compression:  see  page  63;  (3)  for  making  continuous 
sheets:  see  page  65. 

Bessemer  Process. — For  making  steel,  sometimes  called  converting 
process  and,  rarely,  air  refining  process  or  pneumatic  process :  A 
process  for  the  production  of  steel  consisting  in  blowing  air 
through  molten  pig  iron  contained  in  a  suitable  vessel,  whereby 
the  impurities  are  oxidized  and  removed,  and  the  product  is 
obtained  in  a  fluid  condition.  Depending  upon  the  nature  of 
the  lining  of  the  vessel,  there  are  two  modifications:  (a)  acid 
Bessemer  process  (the  original  process,  hence  also  called  simply 
Bessemer  process)  by  which  nearly  all  the  silicon,  carbon,  and 
manganese  are  eliminated;  and  (b)  basic  Bessemer  process  (due 
to  Thomas,  aided  to  some  extent  by  Gilchrist,  and  sometimes 
called  Thomas-Gilchrist  process  or,  on  the  Continent,  Thomas 
process)  in  which  there  is  elimination  of  nearly  all  the  silicon, 
carbon,  and  manganese,  as  in  the  acid  process,  and,  in  addition, 
most  of  the  phosphorus  and  part  .of  the  sulphur. 

The  vessel  or  converter  is  usually  pear-  or  egg-shaped,  the 
bottom  (rarely  one  side)  of  which  is  perforated  with  a  large  number 
of  holes  through  which  a  powerful  blast  of  air  enters  and  passes 
through  the  bath  of  metal,  thereby  oxidizing  the  impurities  which 
go  into  the  slag  if  solid,  or  out  of  the  mouth  of  the  converter 
if  gaseous.  After  the  oxidation  of  the  impurities,  the  bath 
contains  a  certain  amount  of  oxide  and  free  oxygen  which  are 
removed  by  manganese  in  some  form  with  or  without  extra 
carbon. 


i6 


BESSEMER  PROCESS 


The  equipment  of  a  modern  plant  consists  (in  this  country) 
essentially  of  usually  two  to  four  converters,  provided  with  cranes 
and  other  appliances  for  pouring  in  the  molten  pig  and  handling 
the  finished  steel,  etc. ;  cupolas  for  melting  the  pig  (direct  metal 
from  the  blast  furnace,  with  th,e  intervention  of  mixers,  is  now 


FIG.  i. — Converter  in  action. 


generally  used),  and  spiegel  if  rail  steel  is  to  be  made;  blowing 
engines  (in  a  separate  building)  for  supplying  the  blast.  The 
operation  of  the  vessels  is  controlled  by  a  blower  stationed  on 
a  platform  (pulpit)  situated  at  a  little  distance  so  he  can  see  all 
that  is  going  on.  There  are  also  pouring  platforms,  yards,  etc. 
The  converter  is  lined  with  either  acid  or  basic  material  (aeid 


BESSEMER  PROCESS  17 

converter,  basic  converter)  depending  upon  the  practice,  and  is 
mounted  at  about  the  middle  on  trunnions  so  it  can  be  tilted  to 
various  angles  (tilting  converter,  tipping  converter).  In  the 
original  form  it  was  set  on  a  permanent  foundation  and  could  not 
tip  (fixed  converter,  stationary  converter),  this  type  being  still 
employed  in  Sweden  (Swedish  fixed  converter).  The  vessel 
consists  of  a  steel  shell  suitably  lined,  and  comprises  three  sec- 
tions :  the  bottom,  the  middle  part  or  body  (belly),  and  the  upper 
part  or  nose  which  is  open  at  the  top  or  mouth.  The  blast,  at  a 
pressure  of  about  20  to  25  pounds  to  the  square  inch,  is  admitted 
at  the  bottom  through  tuyeres  or  holes  formed  in  bricks  of  a  special 
design,  called  tuyere  bricks  (each  of  which  contains  a  number  of 
holes),  around  which  is  rammed  refractory  material  (bottom  stuff), 
the  whole  being  held  in  a  suitable  casting.  As  the  lining  of  the  bot- 
tom wears  away  much  more  rapidly  than  that  of  the  vessel  proper, 
A.  L.  Holley  designed  one  which  could  be  readily  detached  and 
replaced  by  a  fresh  one  (Holley  movable  or  removable  bottom). 
A  modification  of  this,  where  the  blast  connections  do  not  need 
to  be  broken,  the  bottom  being  simply  slid  out  of  a  frame,  is 
termed  a  draw  bottom.  The  bottom  is  closed  by  an  iron  plate 
(bottom  plate),  between  which  and  the  bottom  of  the  tuyeres  is  an 
open  space  (wind  box,  blast  box,  air  box,  or  tuyere  box)  into 
which  the  blast  is  admitted.  For  basic  practice  the  tuyere  holes 
are  usually  formed  by  ramming  lime  around  pins  which  are  sub- 
sequently withdrawn,  this  forming  what  is  called  the  plug;  a  bot- 
tom made  in  this  way  is  sometimes  termed  a  pin  bottom.  For 
acid  vessels  the  body  and  nose  sections  are  lined  with  blocks  or 
pieces  of  ganister  or  firestone  set  in  ball  stuff  (a  mixture  of  ground 
ganister  or  quartz  and  sand  with  a  little  clay  to  make  the  mass 
plastic).  For  basic  practice  crushed  burnt  dolomite  mixed  with 
tar  or  pitch  (basic  material)  is  rammed  in.  The  bottoms  and 
basic  lining  must  be  dried  very  carefully  before  use.  In  acid 
practice  the  bottoms  last  about  23  to  25,  occasionally  up  to  30, 
heats,  and  the  vessel  linings  up  to  five  or  six  thousand  or  more;  in 
basic  practice  the  bottoms  last  about  20  to  40,  and  the  vessel 
linings  100  to  200  heats.  While  the  vessel  is  in  service  it  is 
patched  between  heats,  and  more  thoroughly  on  Saturday  nights, 
by  throwing  on  the  worn  spots  ball  stuff  or  vessel  patching,  and 
at  the  same  time  any  accretions  (kidneys)  are  pried  off.  If  one 
of  the  tuyeres  burns  through,  the  vessel  may  be  turned  down  while 
the  charge  is  still  in  it,  and  the  defective  tuyere  either  cut  out  and 
a  fresh  one  put  in  its  place,  a  dummy  tuyere  (without  any  holes  in 
it)  inserted,  or  else  it  may  be  noodled,  i.e.,  strips  (noodles  or  rat 
tails)  of  ball  stuff  forced  into  the  holes,  and  an  iron  plate  clamped 
on  over  the  bottom,  and  in  this  last  case  it  is  called  a  blind 
tuyere. 

The  vessel  may  have  one  of  two  forms,  eccentric  or  concentric. 
In  the  former  case  one  side  of  the  nose  is  straight  while  the  other 
is  curved,  thus  bringing  the  center  of  the  mouth  to  one  side  of  the 
vertical  axis;  in  the  latter  case  the  taper  or  curve  of  the  nose  is  uni- 
form all  the  way  around,  which  brings  the  mouth  directly  in  the 
center.  When  a  vessel  is  tipped  on  its  side  (turned  down)  there 
2 


i8 


BESSEMER  PROCESS 


must  be  enough  curve  or  belly  to  permit  the  iron  to  lie  below  the 
level  of  the  tuyeres.  In  the  eccentric  converter,  for  given  cubical 
contents,  the  belly  is  greater.  With  this  type  the  converter  is 
tilted  to  the  same  side  to  receive  the  molten  pig  and  also  to  dis- 
charge the  blown  metal  (pig  iron  purified  by  blowing  air  through 
it).  The  concentric  co  verter  is  turned  down  on  one  side  (iron  side) 
to  receive  the  pig,  and  on  the  other  side  (steel  side)  to  discharge 
the  blown  metal.  In  the  eccentric  converter  the  side  of  greatest 


Bolts  for  fattening  shell 
r/Vo  Trunnion  King 


FIG.  2. — Elevation  of  converter. 
(Harbord  and  Hall,  "Metallurgy  of  Steel".) 

curvature  is  called  the  belly;  the  part  of  this  side  next  the  bottom, 
the  shoulder;  the  middle  of  the  smaller  side,  the  back;  and  the 
upper  part  of  that  side  next  the  nose,  the  breast. 

As  already  stated,  in  the  ordinary  type  of  converter,  the  air  is 
introduced  through  the  bottom,  and  this  is  termed  a  bottom  blown 
converter.  Practically  only  in  the  case  of  baby  Bessemer  con- 
verters, the  air  may  be  introduced  through  tuyeres  or  holes  in  the 
side  for  the  purpose  of  reducing  the  necessary  pressure  of  blast: 
this  is  known  as  a  side  blown  converter.  In  some  of  the  earlier 
types  of  converter  attempts  were  made  to  introduce  the  blast 
through  a  pipe  thrust  down  nearly  to  the  bottom  of  the  bath,  and 


BESSEMER  PROCESS 


this  was  called  an  internally  blown  converter.  One  form  of  tuy- 
ere for  this  purpose,  termed  a  built  up  tuyere,  consisted  of  an  iron 
tube  continued  down  and  attached  to  the  tuyere  proper;  it  was 


Upper  Part  of  Shell  or 
Nose  Section 


FIG.  3. — Section  of  concentric  converter. 
(Harbord  and  Hall,  "Metallurgy  of  Steel".) 

protected  by  hollow  circular  bricks  similar  to  the  sleeve  bricks 
used  for  covering  the  stopper  rod  of  a  ladle.  A  process  devised 
by  Davy  consisted  in  using  an  ordinary  ladle  covered  with  a  lid 


20  i         BESSEMER  PROCESS 

through  which  a  tuyere  passed  nearly  to  the  bottom  of  the  ladle. 
One  style  of  internally  blown  converter,  called  a  tank  converter, 
was  a  lined  iron  tank  with  usually  three  compartments,  the  divid- 
ing walls  of  which  did  not  extend  quite  to  the  bottom,  but  all  the 
way  to  the  top.  When  air  was  blown  into  the  two  outside  com- 
partments, it  passed  down  under  the  partitions  and  up  through 
the  metal  in  the  middle  compartment. 

Acid  Bessemer  Process. — The  vessel  heated  from  the  previous 
charge,  or  by  building  a  fire  within,  is  turned  down  on  its  side  and 
the  molten  pig  iron  run  in  where  it  rests  in  the  belly  below  the 
tuyeres.  The  blast  is  then  turned  on  and  the  vessel  turned  up, 
i.e.,  rotated  to  the  vertical  position.  The  changes  taking  place 
are  indicated  by  the  character  of  the  flame :  at  first  it  is  very  short 
and  dull,  only  the  silicon  and  part  of  the  manganese  burning; 
after  the  silicon  is  gone  the  carbon  is  attacked,  and  the  flame 
grows  longer  and  very  brilliant,  and  the  flame  is  said  to  break 


Back 


Shoulder 


Belly 
FIG.  4. — Converter  parts. 


through.  This  latter  period  is  sometimes  called  the  boil  on 
account  of  the  copious  evolution  of  carbonic  oxide  gas  which  vio- 
lently stirs  up  the  charge.  As  the  flame,  is  very  trying  to  the 
eyes,  special  dark  colored  glasses  (blowers'  glasses)  are  employed 
to  observe  it.  When  the  carbon  is  practically  all  gone  the  flame 
drops  (drop  of  the  flame),  which  is  an  indication  that  the  process 
is  finished.  The  heat  necessary  is  derived  principally  from  the 
combustion  of  the  silicon  and  carbon.  If  the  pig  iron  employed 
contains  too  high  a  percentage  of  silicon  (hot  iron  or  hot  blowing 
iron)  too  muchheat  will  be  generated,  and  the  charge  is  said  to 
blow  hot  (too  hot).  In  this  case  it  is  necessary  to  cool  the  bath 
by  blowing  in  a  little  steam  with  the  blast  or,  better,  by  throwing 
in  steel  scrap  (scrapping).  If,  on  the  other  hand,  the  iron  con- 
tains too  low  a  percentage  of  silicon  (cold  iron  or  cold  blowing 
iron),  the  reverse  action  results,  and  the  charge  is  said  to  blow 
cold.  The  necessary  additions  for  deoxidizing  the  steel  and  giv- 
ing it  the  right  composition  may  be  made  in  the  vessel,  or  more 
usually  in  the  ladle  (see  Recarburization) .  Metal  which  has  been 
blown  too  long  (overblown)  is  overoxidized,  and  hence  inclined 
to  be  wild.  The  charge  is  said  to  have  been  blown  full  when  prac- 


BESSEMER  PROCESS  21 

tically  all  the  carbon  has  been  removed.  If  the  blowing  is  stopped 
shortly  before  this  point  is  reached,  the  metal  is  said  to  be  blown 
young  (rarely  termed  a  hard  blow) .  Slopping  is  where  the  metal 
surges  around  so  violently  that  some  of  it  is  thrown  out.  For 
the  method  of  handling  and  pouring  the  steel,  see  page  57.  In 
this  country  a  heat  takes  from  about  8  to  15  minutes,  and  the 
capacity  of  the  vessels  varies  from  about  8  to  20  tons  per  heat,  the 
output  for  a  pair  of  vessels  being  about  40,000  to  65,000  tons 
per  month. 

Basic  Bessemer  Process. — A  certain  amount  of  lime  is  charged 
with  the  iron,  and  the  process  is  conducted  in  practically  the 
same  way  as  the  acid  until  the  flame  drops.  Here,  instead  of 
turning  the  vessel  down,  the  blowing  is  continued  (sometimes  a 
little  more  lime  is  added)  for  about  four  to  five  minutes,  during 
which  time  the  phosphorus  and  some  of  the  sulphur  are  removed. 
The  end  of  the  operation  is  determined  by  taking  a  test  ingot 
which  is  forged  down,  quenched  in  water,  and  broken;  the  frac- 
ture and  also  the  malleability  indicate  the  state  of  the  process. 
The  period  before  the  drop  of  the  flame  is  called  the  fore  blow,  the 
latter  one  the  after  blow  (rarely  over  blow).  When  ready,  the 
vessel  is  turned  down,  as  much  as  possible  of  the  slag  poured  off, 
and  the  metal  recarburized  in  the  vessel  or  in  the  ladle.  As  a 
small  percentage  of  phosphorus  always  passes  back  into  the  metal 
from  the  slag,  the  heat  must  be  blown  down,  i.e.,  the  phosphorus 
reduced  to  a  lower  percentage  than  that  required  in  the  steel.  A 
heat  takes  about  20  to  25  minutes,  and  one  vessel  can  produce 
about  looo  to  5000  tons  per  month,  depending  on  the  size,  which 
varies  from  about  15  to  25  tons. 

For  the  composition  of  pig  iron  required  for  the  two  processes, 
see  pages  344  and  346. 

Modifications  of  the  Bessemer  process  have  been  concerned 
almost  entirely  with  basic  practice,  as  will  be  seen  below. 

The  Champin  pneumatic  process  was  a  modification  for  making 
wrought  iron  of  which  the  advantages  would. appear  to  be  very 
doubtful.  Pig  iron  was  blown  in  a  converter  in  the  usual  way, 
and  the  blown  metal  was  then  distributed,  by  means  of  a  ladle, 
into  heated  revolving  cylinders,  called  bailers,  and  when  it  had 
solidified  in  balls,  it  was  taken  to  a  squeezer  (see  page  377), 
afterward  given  a  wash  heat,  and  then  worked  down  as  usual 
into  the  desired  product. 

Flohr  adds  (basic  process)  briquets  of  iron  ore,  scale,  etc., 
bound  together  with  about  10%  of  slaked  lime,  and  claims  that 
thereby  the  slag  is  made  thinner,  and  the  dephosphorization 
much  more  rapid. 

Harmet's  process  (basic)  consists  in  treating  the  molten  pig,* 
first  in  an  acid  vessel  to  eliminate  the  silicon,  and  then  in  a  basic 
vessel  to  remove  the  phosphorus  and  the  remainingi  mpurities, 
care  being  taken  that  none  of  the  silicious  slag  from  the  first 
vessel  goes  into  the  second;  this  is  also  termed  repouring  process, 
or  transfer  process. 

The  object  of  George  Lauder's  Process  was  to  leave  the 
desired  amount  of  carbon  in  the  bath  at  the  end  of  the  blow; 


22  BESSEMER  PROCESS 

this  was  to  be  secured  by  first  blowing  and  decarbunzing  only  a 
portion  of  the  charge,  trjte  remainder  being  added  and  blown  only 
sufficiently  to  oxidize  the  silicon;  the  necessary  amount  of  man- 
ganese was  added  as  usual. 

^  The  Massenez  modification  of  the  basic  process  for  treating 
high  silicon  metal  consists  in  charging  only  part  of  the  lime  at  the 
commencement  of  the  process,  and  when  the  carbon  flame  appears 
(showing  the  silicon  has  been  eliminated)  as  much  as  possible  of 
the  slag  is  poured  off;  the  balance  of  the  lime  is  then  added,  and 
the  blowing  completed. 

In  Pettitt's  process  (basic)  iron  oxide  was  used  to  effect  the 
removal  of  the  phosphorus,  irrespective  of  the  lining  of  the 
converter. 

Rochussen  and  Daelen's  process  consisted  in  charging  rich 
iron  ore  into  the  converter  (acid)  with  the  molten  pig,  and  in 
lining  the  converter  with  it  previous  to  the  blow.  The  claim 
was  made  that  the  amount  of  blast  required  was  largely  dimin- 
ished while  the  amount  of  steel  was  increased,  but  the  excessive 
corrosion  which  must  take  place  would  more  than  offset  any 
such  advantages. 

Schiebler's  process  (basic)  consists  in  charging  the  metal  and 
part  of  the  lime  in  the  vessel,  and  both  the  metal  and  slag  are 
poured  out  when  the  first  or  phosphatic  slag  is  formed.  The 
treatment  is  completed  in  a  reverberatory  furnace  having  a  basic 
or  a  neutral  hearth,  with  the  addition  of  the  balance  of  lime  or 
flux. 

Stock  Converter  Process. — "This  is  a  combination  of  an  oil- 
melting  furnace  and  small  side-blown  converter  which  has  lately 
been  erected  at  the  Darlington  Forge,  and  is  said  to  be  giving  very 
good  results.  Materials  are  charged  cold  into  the  previously 
heated  converter;  oil  fuel  under  a  pressure  of  about  40  pounds  to 
the  square  inch  is  supplied  through  flexible  tubing  to  small  tubes 
about  ^{2  of  an  inch  in  diameter,  let  into  the  main  blast  tuyeres, 
which  are  about  2  inches  in  diameter,  and  air  for  combustion,  at  a 
pressure  of  about  i%  pounds,  is  admitted.  When  the  charge  is 
melted,  which  takes  about  i^  hours  for  a  3-ton  charge,  the  con- 
verter is  rotated  to  the  blowing  position,  the  oil  shut  off,  and  the 
bath  of  metal  subjected  to  a  blast  of  air  on  the  surface  for  about 
1 6  to  19  minutes,  when  the  vessel  is  rotated  into  the  teeming  posi- 
tion and  finishing  metal  added  in  the  usual  way.  The  waste 
gases  pass  through  an  economizer  which,  when  the  converter  is  in 
the  blowing  position,  is  opposite  the  mouth  of  the  converter,  and 
this  economizer  contains  the  blast  pipes  through  which  the  blast 
passes  on  its  way  to  the  converter,  and  in  passing  through  which, 
it  is  heated  up  to  a  temperature  of  about  800°  F.  Owing  to  the 
intense  heat  developed  during  melting  and  blowing  with  heated 
blast,  the  converter  has  to  be  lined  with  magnesite  bricks,  but  low 
phosphoric  iron  is  used  and  no  attempt  is  made  to  dephosphorize. 
The  advantages  of  this  converter  are  that  no  impurities  are  taken 
up  by  the  pig  iron  during  melting,  as  in  case  of  coke  melting  in 
cupolas,  and  owing  to  the  hot  blast  being  used  a  very  high  tem- 
perature is  obtained,  insuring  a  very  fluid  metal,  which  makes  the 


BESSEMER  PROCESS  23 

process  particularly  applicable  for  manufacture  of  steel  castings, 
The  vessel  is  mounted  so  that  it  can  be  rotated  into  the  different 
positions  for  charging,  blowing,  and  teeming"  (F.  W.  Harbord 
in  Harbord  &  Hall's  "The  Metallurgy  of  Steel,"  Vol.  I,  p.  78). 

In  the  Swedish  process  the  practice  consists  in  taking  the 
metal  direct  from  the  blast  furnace  without  any  intermediate 
mixer,  and  stopping  blowing  when  the  carbon  has  been  reduced 
to  the  desired  percentage,  which  is  determined  by  the  appearance 
of  the  sparks  and  the  flame,  and  also  by  taking  tests;  a  fixed  con- 
verter is  used  (Swedish  fixed  converter). 

Walrand's  method  for  reducing  the  length  of  the  after  blow  in 
the  basic  process  was  to  add  fluorspar  with  the  lime  to  make  the 
slag  fusible  early  in  the  process.  Although  the  time  for  the 
after  blow  was  reduced,  it  was  found  that  skulls  were  more  likely 
to  be  formed. 

In  Walrand  and  Delattre's  modification  of  the  basic  process, 
the  metal,  after  being  partially  blown  in  an  acid  vessel,  was  run 
into  a  ladle  intended  to  retain  the  silicious  slag,  and  was  then 
poured  into  a  basic  vessel  where  the  blowing  was  completed. 

Walrand  and  Legenisel's  process,  designed  for  use  in  baby 
Bessemer  converters,  consisted  in  the  addition  of  ferro-silicon  to 
the  charge  after  a  preliminary  blow,  to  have  the  steel  hot  enough 
for  making  small  and  intricate  castings. 

In  Warner's  process  (basic)  iron  ore,  containing  too  much  phos- 
phorus for  the  acid,  and  too  little  for  the  basic  process,  is  smelted 
with  the  addition  of  basic  slag  or  phosphoric  material  to  yield 
basic  Bessemer  pig.  This  is  first  desiliconized  in  one  converter 
with  soda  ash  and  limestone,  and  then  taken  to  a  second,  and 
finished  as  usual. 

Ordinary  converters  vary  from  about  5  to  25  tons  capacity  per 
heat;  for  making  castings,  smaller  sizes  are  generally  employed, 
up  to  about  5  tons,  and  are  called  baby  Bessemer  converters ; 
only  in  contradistinction  to  these,  the  ordinary  sized  ones  are 
termed  large  or  big  Bessemer  converters.  Various  modifica- 
tions of  converters,  as  mentioned  below,  have  been  made  from 
time  to  time,  but  principally  of  a  mechanical  nature.  Sir  Hfenry 
Bessemer  covered  the  ground  so  completely  that  a  radical  depar- 
ture seems  impossible. 

In  the  Cambier  converter,  which  is  of  small  size,  the  blast 
enters  at  the  side,  not  through  tuyeres,  but  through  holes  in  the 
lining  which  are  inclined  downward  at  a  slight  angle. 

The  Clapp-Griffith  converter  is  essentially  a  small,  high,  side- 
blown,  stationary  vessel,  with  a  spout  or  slag  hole  at  such  a  level 
that  the  slag  runs  out  of  it  during  the  boil.  This  feature  appears 
to  be  the  only  real  novelty. 

The  Davy  portable  converter  was  a  small  converter  of  the  usual 
type,  but  was  so  constructed  that,  after  the  charge  had  been 
blown  and  made  ready  for  casting,  it  could  be  carried  to  the  molds 
and  the  metal  poured  directly  into  them  without  the  intervention 
of  a  ladle. 

Deighton's  method  of  operating  was  to  have  at  least  two  spare 
vessels,  one  of  which  would  always  be  ready  to  replace  a  vessel 


24  BESSEMER  PROCESS 

requiring  relining,  so  the  only  lost  time  would  be  that  necessary 
for  changing. 

In  Eldred's  converter  the  air  pipe  to  the  blowing  engine  is  con- 
nected with  an  auxiliary  furnace  in  such  a  way  that  either  pure 
air  or  part  air  and  part  waste  gases  can  be  used  for  blowing  the 
charge,  the  object  being  to  control  the  temperature  of  the  charge 
and  prevent  it  from  getting  too  hot. 

The  Hatton  converter  was  claimed  to  be  an  improvement  of  the_ 
Clapp- Griffith,  having  a  movable  bottom,  and  regulating  valves" 
for  the  blast;  it  also  lacked  the  slag  spout  or  hole. 

Laureau's  converter  was  a  small,  tilting,  side-blown  converter, 
with  the  tuyeres  placed  high,  and  set  in  a  separate  ring  which 
could  be  easily  removed  and  replaced,  as  the  lining  in  the  neigh- 
borhood of  the  tuyeres  is  worn  away  most  rapidly. 

In  the  form  devised  by  T.  Levaz,  the  converter,  which  is  of 
small  size,  and  tilting,  with  side  blast,  has  the  upper  part 
enlarged  to  form  a  pocket  to  receive  the  metal  when  the  vessel  is 
turned  down.  Murdock's  converter  has  essentially  the  same 
feature. 

The  Paxsbn-Deemer  converter  is  a  small,  tilting,  side-blowing 
vessel,  the  tuyeres  being  placed  at  the  level  of  the  metal  so  the  . 
blast  strikes  it  partly  above  and  partly  below  the  surface. 

Raapke's  converter  is  of  small  size  and  of  the  fixed  type,  with 
tuyeres  on  one  side  and  tapping  hole  on  the  other.  Oxygen  is 
added  to  the  blast,  and  means  are  employed  for  utilizing  the  heat 
evolved  for  heating  the  blast  and  for  preparing  the  oxygen. 

The  Robert  converter  has  a  D-shaped  cross-section  with  hori- 
zontal tuyeres,  slightly  inclined  to  the  radial,  on  the  flat  side  only, 
giving  the  bath  a  whirling  motion;  it  is  of  small  size  and  is  tipping. 
The  original  form  was  circular,  and  was  called  the  Walrand  con- 
verter, later  modified,  the  Walrand-Delattre,  this  being  further 
modified  by  Robert  to  the  form  described. 

In  Sherk  and  Rutter's  converter,  which  is  tilting,  there  are  a 
number  of  tuyeres  so  placed  that  only  a  small  portion  of  the 
blast  enters  below  the  surface  of  the  metal,  and  by  tilting  the  con- 
verter the  proportion  may  be  modified. 

In  the  Stoughtpn  or  long  tuyere  type,  which  is  a  side-blown  con- 
verter of  small  size,  the  tuyeres  are  on  one  side,  discharging  the 
blast  immediately  at  the  surface  of  the  metal.  The  lining  on  the 
tuyere  side  is  thicker  than  elsewhere,  which  serves  to  increase  the 
time  the  vessel  can  remain  in  service  without  relining,  and  also 
insures  better  direction  of  the  blast. 

Thomas'  converter  was  similar  to  a  stationary  converter  in 
form,  but  was  mounted  on  rockers  so  it  could  be  inclined  with 
less  costly  mechanism  than  that  required  by  the  regular  tilting 
type. 

The  Tropenas  process  employs  a  small,  tilting,  side-blown 
converter  with  two  rows  of  tuyeres  on  one  side.  The  lower  set 
directs  the  blast  on  the  surface  of  the  metal,  and  the  upper  set 
(called  tuyeres  of  combustion)  supply  air  for  burning  the  car- 
bon monoxide  to  carbon  dioxide,  thereby  getting  a  greater  heat 
efficiency. 


BESSEMER  STEEL— BILLET  TEST  25 


The  Wills  converter  is  a  small  side-blown  vessel  consisting  of 
two  sections,  a  ladle  section  and  a  dome  section;  the  tuyeres  are 
arranged  to  give  the  metal  a  rotary  motion.  The  metal  may  be 
tapped  (a)  out  of  a  hole  at  the  bottom  of  the  ladle  section,  (b) 
through  the  nose  by  turning  the  converter  down,  or  (c)  the  ladle 
section  can  be  removed,  and  the  metal  poured  directly  from  this 
into  the  molds. 

The  Witherow  converter  is  very  similar  to  Hatton's,  but 
claimed  to  be  simpler  as  regards  the  controlling  mechanism  for  the 
blast. 

Wittnufftt's  converter  was  an  early  type  of  fixed  converter 
with  tuyeres  on  each  side  inclined  downward. 

The  Zenzes  converter  is  a  small,  tilting,  side-blown  converter 
varying  only  in  slight  details  from  others  of  this  type. 
Bessemer  Steel. — Steel  made  by  the  Bessemer  process. 
Besson. — "Iron  of  Bessemer:"  name  suggested  for  iron  or  low- 
carbon  steel  produced  by  the  Bessemer  (pneumatic)  process. 
Best  or  B. — A  brand  of  wrought  iron  plate  or  bar  equivalent  to  No.  3 
quality,  or  that  grade  which  is  just  superior  to  the  commonest. 
It  is  obtained  by  piling,  reheating,  and  rerolling  either  No.  i  and 
No.  2  iron,  or  all  No.  3  brands.     The  best  plates  of  the  first-class 
houses  are,  however,  equal  to  the  best,  best  best,  and  treble  best 
of  other  firms  (Horner). 
Best  Best  or  B.  B. — A  brand  of  wrought  iron  plate  or  bar  indicating 
a  superior  quality  obtained  by  piling,  reheating,  and  rerolling  best 
or  No.  3  bars  (Horner). 

Best  Best  Best  or  B.  B.  B.,  or  Treble  Best.— A  brand  of  wrought 
iron  plate  or  bar  indicating  the  best  quality  of  iron  made.  It  is 
obtained  by  repiling,  reheating,  and  rerolling  the  best  best  qual- 
ity (Horner). 

!  Best  Bar. — See  page  378. 
•'  Best  Charcoal  Iron. — Wrought  iron  made  by  some  charcoal-hearth 

process. 

Best  Tap  (Eng.).— See  page  376. 
Beta  I;  Beta  II.— See  page  280. 
>  Beta  (j8)  Iron. — See  pages  264  and  272. 
Beta  Iron  Theory;  Beta  Theory. — Of  hardening:  see  page  279. 
!  Beton  (French). — Concrete  beton  arme,  reinforced  concrete. 
}  Betty  (Eng.). — A  crowbar, 
|  Bibasic. — See  page  87. 
i  Bickley  Mill. — See  page  417. 
!  Biedermann  and  Harvey  Process. — See  page  317. 
Big  Bessemer  Converter. — See  page  23. 
i  Billet. — See  page  411. 

i  Billet  Chute. — A  chute  or  inclined  bin  for  loading  billets  on 
cars,  and  generally  operated  in  connection  with  a  billet 
conveyor. 

Billet  Conveyor. — A  device  for  handling  billets,  usually  consisting 
of  an  endless  chain  of  small  rollers  passing  around  and  driven  by 
drums. 

Billet  Mill.— See  page  411. 
Billet  Test.— See  page  483. 


26  BILLETING  ROLLS— BLANK 

Billeting  Rolls/ — See  page  411. 

Billing  Process. — (i)  Of  casting:  see  page  60;  (2)  for  fluid  compres- 
sion: see  page  63. 

Bimetallic  Thermometer. — See  page  205. 

Bimetallic  Wire. — See  page  509. 

Binary  Alloy.— See  Alloy. 

Binary  Compound.— See  page  88. 

Binary  Theory. — See  page  89. 

Binding  Coal.— See  Coal. 

Binding  Material. — A  material  used  to  bind  (usually)  refractory 
substances  together;  (i)  by  combining  with  them,  as  a  small  per- 
centage of  lime  in  silica  bricks,  (2)  by  being  more  fusible,  as  clay 
in  sand,  and  (3)  carbonaceous  compounds  which  lose  their  volatile 
matter  on  heating,  such  as  sugar,  flour,  oil,  etc. 

Bink  Process. — See  page  71. 

Binocular  Microscope. — See  page  285. 

Bird's  Mouth  Weld.— See  page  502. 

Birmingham  Wire  Gage. — See  page  188. 

Bismuth.r— Bi;  at.  wt.,  208.5;  rnelt.  pt.,  268.3°  C.  (515°  F.)  sp.gr., 
9.75.  A  white  metal  with  a  faint  reddish  tinge.  Usually  occurs 
in  the  uncombined  condition.  It  is  not  of  importance  in  the 
manufacture  of  steel,  and  appears  to  act  much  like  antimony. 

Bite. — Of  rolls:  see  page  407. 

Bituminous  Coal ;  Shale. — See  Coal. 

Black  Annealing. — See  page  431. 

Black  Band. — A  kind  of  iron  ore:  see  page  244. 

Black  Body;  Black  Body  Temperature. — See  page  207. 

Black  Center.— See  page  178. 

Black  Clay.— See  page  302. 

Black  Edged  Plate. — See  page  432. 

Black  Fracture/ — See  page  178. 

Black-heart  Castings;  Malleable. — See  page  258. 

Black  Heat;  Hot. — Color  temperature:  see  page  210. 

Black  Iron  Objects. — See  page  364. 

Black  Iron  Sand. — See  page  244. 

Black  Japan. — See  page  365. 

Black  Loam. — See  page  301. 

Black  Oxide  (rare). — Oxide  (of  iron). 

Black  Patch.— See  page  432. 

Black  Pickling. — See  page  431. 

Black  Plate. — See  page  431. 

Black-red  Heat. — Color  temperature :  seepage  210. 

Black  Sand. — In  a  foundry,  old  sand. 

Black  Temperature. — See  page  207. 

Black  Wash  Coating. — See  page  298. 

Blacking ;  Blacking  Bag. — See  page  298. 

Blacklead  Blacking. — See  page  298. 

Blacklead  Crucible. — See  page  in.    9 

Blair ;  Blair-Adams  Process. — See  page  137. 

Blank. — A  piece  of  metal  prepared  especially  to  be  manufactured 
into  some  particular  object. 


BLANKET— BLAST  FURNACE         27 

Blanket. — In  connection  with  a  flame,  to  reduce  the  proportion  of 
air  to  make  it  as  reducing  as  possible. 

Blaseofen. — See  page  147. 

Blast. — The  name  given  to  air  under  pressure  used  for  purposes  of 
combustion,  etc.,  as  in  the  blast  furnace  or  the  Bessemer  con- 
verter; in  some  cases  for  cooling  purposes,  as  in  the  case  of  tools. 
If  preheated,  it  is  termed  hot  blast  or  warm  blast;  if  not  pre- 
heated, cold  blast.  A  blast  under  considerable  pressure  is  some- 
times referred  to  as  a  cutting  blast ;  if  weak,  a  soft  blast. 

Blast  Box. — See  page  17. 

Blast  Furnace. — A  shaft  furnace  (see  page  181),  in  its  early  days 
called  a  high  furnace,  supplied  with  blast  for  producing  pig  iron 
by  smelting  iron  ores.  It  is  continuous  in  operation,  the  solid 
raw  materials  being  charged  at  the  top,  and  the  molten  pig  iron 
and  slag  collected  at  the  bottom  and  tapped  out  at  intervals. 
Large  furnaces  are  about  80  to  100  feet  high;  have  an  output  up 
to  600  or  700  (commonly  300  to  500)  tons  per  day,  and  employ 
blast  at  a  pressure  of  5  to  25  (usually  lo'to  15)  pounds  per  square 
inch,  and  at  a  temperature  of  about  900°  to  1400°  F.  (485°  to  760° 
C.).  The  modern  equipment  consists  essentially  of  the  furnace 
proper  or  stack ;  powerful  blowing  engines  for  compressing  the  air 
for  the  blast ;  stoves  for  preheating  the  blast;  appliances  for  charg- 
ing the  raw  materials;  a  cast  house  for  disposing  of  the  molten 
iron;  and  a  power  station. 

Stack. — There  are  three  well  denned  divisions,  usually  circular — 
practically  now  never  oval  or  square — in  section.  At  the  bottom — 
is  the  hearth  (well,  laboratory,  or  crucible)  of  cylindrical  shape; 
above  this  the  walls  diverge,  forming  an  inverted  truncated  cone, 
called  the  bosh  (also  th£  name  for  the  greatest  diameter  of  the 
furnace),  above  which  the  walls  converge  to  the  top  (throat  or 
mouth),  forming  another  truncated  cone  set  upright.  In  a 
furnace  with  saucer  bosh  or  belly  walls,  the  walls  above  the 
bosh,  instead  of  being  straight,  are  slightly  convex.  The  design 
(lines)  of  a  furnace  depend  both  upon  the  nature  of  the  ore  and 
the  kind  of  product  desired.  For  the  fine,  soft  Mesaba  ores  it  is 
usual  to  sharpen  the  angle  of  the  bosh,  decrease  the  height  of 
the  bosh,  and  increase  the  diameter  of  the  hearth;  for  example, 
where  high  silicon  is  desired  in  the  pig,  the  diameter  of  the  hearth 
is  decreased.  The  furnace  is  built  of  fire-brick  (cold-blast  fur- 
naces are  also  built  of  stone),  usually  but  not  always  incased  in  a 
steel  jacket  extending  part  or  all  the  way  up.  The  fire-brick 
portion  is  referred  to  as  the  lining.  The  section  above  the  bosh 
is  supported  on  a  mantle  (mantel)  ring  (lintel  plate)  and  columns. 
Up  to  a  certain  distance  from  the  bottom  of  the  furnace  the  walls 
are  protected  from  corrosion  by  cooling  plates  of  bronze  or  other 
metal  through  which  water  circulates;  sometimes  water  is  caused 
to  flow  down  the  outside.  Within  the  past  few  years  thin-lined 
furnaces  have  been  constructed  where  the  thickness  of  the  lining 
has  been  greatly  reduced;  the  lining  is  entirely  cased  in  steel 
plates  and  the  cooling  plates  are  continued  practically  up  to  the 
top;  the  object  is  the  better  maintenance  of  the  lines,  and  inci- 
dentally to  save  on  the  cost  of  construction. 


28  BLAST  FURNACE 

Blast. — Formerly  the  blast  was  always  used  cold  (cold  blast) 
but  this  practice  is  now  restricted  to  a  few  small  furnaces  as  a 
rule  employing  charcoal  for  fuel.  Hot  blast  was  introduced  by 
Neilson  about  1828  and  effected  a  great  economy  in  fuel.  The 
blast  temperature  varies  from  about  900°  to  1200°  F.  (480°  to 


FIG.  5. — Blast  furnace  and  hot  blast  stoves. 

650°  C.)  in  this  country,  and  up  to  about  1600°  or  even  1800°  F. 
(870°;  980°  C.)  in  some  European  practice.  The  average  tem- 
perature carried  on  furnaces  burdened  with  Mesaba  ore  seldom 
exceeds  1100°  F.  (595°  C.),  ranging  far  lower  than  that  commonly 
applied  in  European  practice  and  lower  also  than  on  most  of  our 


BLAST  FURNACE 


29 


eastern  furnaces  using  mag- 
netic  ores,  due  to  the 
Mesaba  ores  being  more 
easily  reducible  (Brassert). 

Dry  Blast.— The  practical 
application  of  this  to  blast 
furnace  work  is  compara- 
tively recent  and  is  due 
primarily  to  the  Gayley 
process  which  will  be  de- 
scribed later,  after  consider- 
ing the  general  conditions 
involved. 

The  blast  does  not  consist 
solely  of  oxygen  and  nitro- 
gen, but  contains,  in  addi- 
tion to  these  elements,  vary- 
ing amounts  of  moisture 
(among  other  substances) 
depending  upon  the  temper- 
ature and  the  degree  of 
liumidity  of  the  air.  The 
amount  of  moisture  per 
cubic  foot  of  air  (at  atmo- 
spheric pressure)  will  vary 
from  less  than  i  grain  in 
winter  to  over  8  grains  in 
summer,  and  while  even  this 
latter  amount  might,  at 
first  glance,  seem  inconsid- 
erable, a  brief  consideration 
of  the  volume  of  air  passing 
through  a  modern  furnace 
will  show  that  this  is  far 
from  being  the  case.  "With 
air  containing  i  grain  of 
water  per  cubic  foot,  there 
is  passed  into  the  furnace, 
for  each  1000  cubic  feet 
used  per  minute,  practically 
i  gallon  of  water  per  hour. 
A  furnace  of  average  size  in 
the  Pittsburgh  district  con- 
sumes about  40,000  cubic 
feet  of  air  per  minute,  which 
would  pass  into  the  furnace 
40  gallons  of  water  per  hour 
for  each  grain  of  moisture 
contained  in  a  cubic  foot  of 
air"  (Gayley). 

The  amount  of  moisture  varies  not  only  from  day  to  day  but 
from  hour  to  hour,  and  numerous  investigations  have  shown  that 


PIG.  6. — Section  of  one  of  the 
Duquesne  blast  furnaces. 


30  BLAST  FURNACE 

the  slightest  change  has  a  very  marked  effect  upon  the  working 
of  the  furnace.  The  amount  of  moisture  from  the  air,  while  small 
as  compared  with  that  contained  in  the  materials  charged  in  the 
top,  has  a  more  noticeable  effect  for  the  reason  that,  entering  at 
the  tuyeres,  it  is  immediately  decomposed  by  the  incandescent 
coke  into  carbon  monoxide  and  hydrogen,  a  reaction  which 
absorbs  a  large  amount  of  heat,  while  the  moisture  contained  in 
the  materials  charged  in  the  top  is  simply  evaporated  and  driven 
off  with  the  hot  gases  near  the  top  of  the  furnace. 

It  has  been  observed  that,  as  a  rule,  furnaces  worked  better  in 
winter  than  in  summer,  and  the  reason  this  difference  has  not 
been  more  marked  would  seem  to  be  on  account  of  the  variation 
in  the  percentage  of  moisture  in  the  air.  The  aim  of  the  process  is 
not  alone  to  remove  as  much  of  the  moisture  as  possible,  but  also 
to  render  the  percentage  constant,  and  with  it  the  working  of  the 
furnace. 

Various  methods  for  the  drying  (desiccation)  of  air  have  been 
suggested  and  employed.  These  may  be  divided  into  those 
which  make  use  of  some  absorbent  substance,  such  as  calcium 
chloride  and  sulphuric  acid,  and  those  which  are  based  on  extract- 
ing the  moisture  by  refrigeration.  In  connection  with  the  use  of 
calcium  chloride  it  should  be  noted  that  before  complete  expul- 
sion of  the  combined  water  there  exists  what  is  known  as  the 
tardy  hydrate  with  less  than  one  molecule  of  H2O;  this  is  removed 
only  by  igneous  fusion,  and  in  view  of  the  added  cost  no  advan- 
tage is  gained.  One  of  the  first  records  is  that  of  a  patent  granted  to 
Mushet  in  1879  for  the  use  of  calcium  chloride,  etc.  The  Fryer 
process  consists  in  passing  the  air  over  broken  pieces  of  fused 
calcium  chloride,  which  is  subsequently  regenerated  partly  in 
special  boilers  and  then  by  fusion.  In  the  Cremer  process  the 
air  is  passed  (either  by  suction  or  under  pressure)  through  a 
chamber  with  shelves  bearing  calcium  chloride,  sulphuric  acid, 
etc.  Regeneration  was  effected  without  removal  of  the  drying 
agents  by  subjecting  them  to  a  current  of  hot  air  or  waste  gases 
by  means  of  a  false  bottom  in  the  shelves.  The  Eisner  process 
employs  calcium  chloride  and  is  carried  out  by  means  of  two 
drums:  An  upper  drum  in  which  the  desiccation  of  the  air  is 
effected  and  a  lower  in  which  the  calcium  chloride  is  regenerated. 
Harbord  employs  various  porous  substances  such  as  peat  or 
pumice  stone  to  hold  a  concentrated  solution  of  calcium  chloride 
which  is  regenerated  in  place. 

Gayley  Dry  Blast  Process. — The  apparatus  consists  of  a  refrig- 
erating chamber  in  which  are  coils  of  pipe  through  which  brine, 
cooled  to  a  temperature  below  the  freezing  point  of  water  by  an 
ammonia  refrigerating  machine,  is  passed.  The  air  circulates 
around  these  pipes  and  deposits  on  them  its  moisture  as  snow  or 
ice.  When  the  deposit  becomes  too  thick  (about  every  three 
days)  it  is  melted  off  by  passing  heated  brine  through  the  pipes. 
The  desiccated  (cooled)  air  is  then  introduced  into  the  blowing 
engines  and  goes  thence,  in  the  usual  manner,  through  the  stoves 
and  into  the  furnace. 
Dry  blast  was  first  tried  with  Isabella  Furnace  No.  i  of  the 


BLAST  FURNACE  31 

Carnegie  Steel  Company,  on  August  n,  1904.  The  dry  blast 
was  not  introduced  all  at  once,  but  at  first  only  one-third  was 
used.  At  the  same  time  the  burden  was  gradually  increased 
until,  at  the  end  of  two  weeks,  it  had  reached  an  increase  of 
20%.  It  was  found  that  the  saving  in  coke  amounted  to 
about  400  pounds  per  gross  ton  of  pig  iron  produced  on  a  former 
consumption  of  a  little  less  than  2200  pounds.  As  the  water 
extracted  from  the  blast  amounted  to  about  69  pounds  per  ton  of 
iron,  corresponding  to  about  80  pounds  of  coke,  this  would  not 
account  for  all  the  saving.  This  subject  has  occasioned  consider- 
able discussion  by  practical  blast  furnacemen  and  scientists,  and 
many  and  various  are  the  explanations  which  have  been  offered 
to  account  for  the  results  obtained.  That  now  generally  recog- 
nized as  the  correct  solution  was  advanced  by  J.  E.  Johnson,  Jr., 
and  is  based  upon  a  critical  temperature  in  the  furnace  which 
must  be  surpassed  to  accomplish  the  necessary  reactions.  The 
difference  between  this  critical  temperature  and  that  actually 
attained  marks  the  efficiency  of  the  furnace.  It  is  therefore 
obvious  that  a  slight  increase  when  figured  as  a  percentage  of  the 
temperature  above  the  critical  is  very  much  greater  than  when 
figured  as  a  percentage  of  the  actual  temperature. 

Among  the  attendant  advantages  is  the  fact  that,  owing  to  the 
greater  density  of  the  air  as  introduced  into  the  blowing  tubs, 
fewer  revolutions  of  the  engines  are  required,  and  the  decreased 
cost  from  this  nearly  offsets  that  of  operating  the  refrigerating 
plant.  Another  advantage  is  found  in  the  smaller  percentage  of 
flue  dust  produced,  particularly  when  fine  ores  are  being  used. 
In  the  case  of  the  Isabella  Furnace  this  was  reduced  from  5  to 
i  %.  The  process  is  in  use  at  a  number  of  blast  furnace  plants 
both  in  the  United  States  and  abroad. 

In  the  Miles  dry  blast  process  the  air,  after  compression,  is 
desiccated  by  cooling  in  two  steps  by  water  sprays:  first  by 
ordinary  river  water,  and  second,  by  refrigerated  water.  It 
depends  on  the  fact  that,  to  secure  the  same  degree  of  desicca- 
tion, the  cooling  need  not  be  carried  so  far  after  compression  as  if 
uncompressed.  It  is  claimed  that  with  blast  at  10  pounds  pres- 
sure the  moisture  can  be  reduced  to  about  1.38  grains  per  cubic 
foot  of  air  when  refrigerated  water  is  used;  and  still  further  when 
brine  (which  can  be  cooled  to  a  lower  temperature)  is  substituted. 
The  blast  is  introduced  near  the  bottom  of  the  bosh  through  a 
number  of  pipes  or  tuyeres  (twyers,  tweers),  usually  8  to  16  in 
number,  which  are  protected  from  burning  by  being  encased  in 
water-cooled  metal  castings,  tuyere  blocks  (tuyere  arch  cooler). 
The  opening  in  the  furnace  wall  is  called  the  tuyere  arch,  and  the 
space  between  this  and  the  block,  the  breast  (water  breast). 
Depending  upon  the  point  at  which  the  cooling  water  is  intro- 
duced, the  tuyere  is  said  to  be  side-fed  or  bottom-fed.  The 
overhang  of  a  tuyere  is  the  amount  it  projects  into  the  furnace 
beyond  the  inner  wall.  The  Scotch  tuyere  is  of  cast  iron,  with  a 
wrought-iron  coil  of  pipe,  for  the  cooling  water,  cast  in  the  walls. 
The  Lancashire  tuyere  is  a  hollow  truncated  cone  with  double 
walls,  the  cooling  water  flowing  between  them.  An  open  spray 


32  BLAST  FURNACE 

tuyere  is  somewhat  similar  to  the  above,  but  the  rear  end  is  open 
(open  tuyere),  and  the  walls  are  kept  cool  by  jets  of  water  from 
perforated  pipes  inside.  In  the  spreader  tuyere,  which  is  of  a 
somewhat  similar  type,  the  water  is  distributed  over  a  sheet  to 
cool  the  upper  part  of  the  shell,  a  jet  of  water  cooling  the  nose, 
and  the  water  running  back  over  the  bottom  to  the  outlet.  A 
vacuum  or  exhaust  tuyere  is  one  from  which  the  water  is  sucked 
out,  instead  of  being  forced  through,  to  lessen  the  leakage  in  the 
furnace  if  the  tuyere  breaks.  The  blast  from  the  stoves  is  led 
into  a  large  pipe  (bustle  pipe)  surrounding  the  furnace  and  above 
the  tuyeres  with  which  it  is  connected. 

At  a  point  near  the  top  of  the  hearth  is  a  hole  for  tapping  the 
slag  (slag  notch,  cinder  notch,  flushing  hole,  monkey),  and  lower 
down  and  to  one  side  is  the  iron  notch,  metal  notch  or  tapping 
hole  for  tapping  out  the  molten  iron.  In  one  type  of  furnace 
there  was  a  plate  (guard  plate)  over  the  cinder  hole  with  the  tap- 
ping hole  in  it.  In  modern  furnaces  the  hearth  is  entirely  within 
the  furnace,  and  is  called  a  closed  hearth,  the  contents  being 
tapped  through  a  hole  in  the  wall.  This  arrangement  was  first 
introduced  by'Liirmann,  and  was  called  a  closed  front  (Lurmann 
front).  "It  was  formerly  the  custom  to  have  an  open  fore  part 
(open  front).  .In  front  of  the  furnace  there  was  an  arched-over 
opening  extending  from  the  furnace  bottom  to  a  little  above  the 
level  of  the  tuyeres;  the  sides  and  roof  of  this  opening  formed  a 
cavity  known  as  the  fore  hearth.  A  wall  of  fire-brick  called  the 
dam,  was  carried  to  the  tuyere  level;  it  formed  the  back  of  the  fore 
hearth,  and  was  supported  by  a  stone  (dam  stone)  or  cast-iron 
dam  plate ;  in  the  dam  plate  was  a  vertical  slit,  which  was  stopped 
with  loam,  and  which  allowed  of  a  tapping  hole  being  made  at 
any  convenient  level,  while  the  excess  of  cinder  ran  off  through  a 
semicircular  cinder  notch.  The  arch  above  the  dam  was  called  the 
tymp  (timp) ;  it  was  kept  in  position  by  a  tymp  plate  (tymp  stone) 
of  cast  iron,  and  generally  cooled  by  running  water"  (Turner).  In 
Lunnann's  closed  front  arrangement  the  slag  was  tapped  through 
a  water-cooled  tuyere  (scoria  block)  situated  in  a  water-cooled 
cast-iron  plate  (scoria  plate). 

At  the  top  of  the  furnace  is  the  charging  arrangement  consist- 
ing usually  of  two  bells,  a  large  one  below,  and  a  smaller  one 
above,  each  fitting  in  a  hopper  (bell  and  hopper,  cup  and  cone), 
and  so  arranged  that  only  one  is  lowered  at  <a  time,  thus  prevent- 
ing the  escape  of  gas.  Various  forms  of  ore -distributing  devices 
(distributors)  have  been  designed  to  secure  an  even  distribution 
of  the  charge  within  the  furnace;  for  example  there  may  be  an 
apron  either  fixed  (Killeen  distributor)  or  movable  (McDonald 
distributor)  between  the  large  bell  and  the  inwall  (interior  wall) 
to  deflect  the  descending  charge.  A  revolving  top  is  where  the 
chute  or  bell  is  revolved  a  certain  amount  for  each  addition;  the 
older  form  is  accordingly  distinguished  as  a  stationary  top. 

Charging. — The  ore  is  kept  in  huge  piles  (stock  pile)  in  a 
yard,  and  is  handled  by  large  traveling  cranes  (ore  bridge, 
gantry  crane).  It  is  loaded  into  bins  from  which  it  is  run  into 
small  hopper-bottom  cars  (larry,  lorry)  equipped  with  scales  for 


BLAST  FURNACE  33 

weighing  it,  and  from  these  is  dumped  into  the  buckets  or  boxes 
(skips)  which  are  hoisted  to  the  top  of  the  furnace  up  an  inclined 
bridge  (skip  bridge),  and  dumped  automatically  on  the  upper 
bell.  Depending  upon  whether  there  is  a  single  or  a  double  track 
(in  the  latter  case  one  skip  ascending  while  the  other  is  descend- 
ing) it  is  single  or  double-skip  charging.  The  limestone  is  simi- 
larly handled;  the  coke  is  measured  by  volume  (occasionally 
weighed),  the  contents  of  the  skip  representing  a  definite  weight. 
This  method  is  known  as  skip  charging.  The  older  method,  now 
seldom  employed  for  new  furnaces,  is  to  weigh  the  materials  in 
wheel-barrows  which  are  raised  to  the  top  of  the  furnace  by  an 
elevator  (hoist,  lift),  and  dumped  around  the  bell  by  hand  (bar- 
row charging).  One  complete  unit  or  charge  of  ore,  coke,  and 
limestone  is  called  a  round. 

Blast  Furnace  Gas. — The  gas  is  taken  of!  at  the  top  of  the  fur- 
nace through  one  or  more  openings  connecting  with  a  large  pipe 
(downcomer)  which  leads  to  a  large  chamber  (dust  catcher,  dust 
chamber)  on  the  ground,  where,  the  direction  of  the  gas  being 
changed,  most  of  the  dust  (flue  dust),  consisting  of  a  mixture  of 
fine  ore  and  coke  together  with  a  little  lime,  carried  over  mechan- 
ically, is  deposited.  As  a  rule  no  water  is  employed  (dry  dust 
catcher),  but  the  gas,  if  to  be  used  for  gas  engines,  is  later  purified 
by  being  led  through  a  chamber  (scrubber)  where  it  is  sprayed 
with  water  and  passed  over  moistened  bricks.  In  such  case  the 
gas  from  the  dust  catcher  is  known  as  raw  or  dirty  gas ;  after  a 
preliminary  treatment,  as  primary  gas;  and  after  final  treatment, 
as  clean  gas  or,  in  some  cases,  secondary  gas.  There  are  various 
systems;  dry  cleaning  without  water,  and  wet  cleaning  or  wash- 
ing with  water  sprays.  In  the  latter  process,  at  present  more 
commonly  used,  the  dust,  collected  in  reservoirs  as  mud,  is  called 
sludge  or  pond  sludge.  Compound  gas  was  a  name  suggested 
for  blast  furnace  gas  passed  through  a  coke  oven,  whereby  it  was 
claimed  a  gas  was  produced  containing  less  carbon  dioxide  and  less 
nitrogen  then  when  used  separately.  A  marked  increase  in 
efficiency  is  shown  when  purified  gas  is  used  for  heating  the  stoves. 
Part  of  the  gas  is  used  for  heating  the  stoves,  and  part  for  burning 
under  boilers  or  in  gas  engines.  Owing  to  the  high  percentage  of 
nitrogen  the  calorific  power  of  the  gas  is  low  (85  to  100  B.T.U.). 
Its  composition  is  approximately: 


Carbon  monoxide, 
Carbon  dioxide, 
Nitrogen, 
Hydrogen, 
Hydrocarbons, 

24%  bv  volume, 

12%    "            " 
60%    "            " 
2%    "            " 
2%    "            " 

24%  by  we 

17%  " 
58%  " 

0.2%    " 

0.8%  " 

ght. 

« 
i 

The  top  of  the  furnace  may  be  provided  with  a  number  of  counter- 
weighted  doors  (explosion  doors)  which  open  automatically  to 
relieve  any  excessive  pressure  of  gas  within,  or  these  may  be 
omitted  (closed  top)  and  the  top  designed  of  sufficient  strength 
to  withstand  this,  thus  preventing  solid  material  from  being 
blown  out.  A  door  or  valve  which  can  be  opened  from  the  ground 
3 


34  BLAST  FURNACE 

to  relieve  the  pressure  is  called  a  bleeder.  In  early  practice,  when 
the  gas  was  allowed  to  escape  the  furnace  had  an  open  top,  the  gas 
burning  on  coming  in  contact  with  the  air.  In  this  case  a  chim- 
ney (tunnel  head)  was  provided  to  carry  it  away  from  the  charg- 
ing hole  for  the  protection  of  the  workmen. 

Stoves  for  heating  the  Blast. — These  are  cylindrical  in  form,  up 
to  100  feet  high  or  a  little  over,  and  consist  of  a  steel  or  iron  shell 
lined  with  fire-bricks  which  form  a  number  of  flues  or  passages. 
Depending  upon  the  number  and  the  arrangement  of  the  flues, 
they  are  known  as  two-pass  stoves,  three-pass  stoves,  etc.  They 
are  regenerative  (see  page  203)  in  principle,  gas  being  introduced 
and  burned  at  the  bottom,  the  products  of  combustion  going  out 
at  the  top,  and  the  blast  being  forced  through  in  the  opposite 
direction,  the  two  operations  not  occurring  at  the  same  time.  A 
large  furnace  generally  has  four  stoves,  three  of  which  are  being 
heated  (on  gas)  while  the  fourth  is  heating  the  blast  (on  wind). 
The  earlier  stoves  had  cast-iron  pipes  (pipe  stove,  metal  stove,  or 
direct  firing  stove)  heated  externally,  and  through  which  the 
blast  passed  continuously  on  the  recuperative  (see  page  204) 
principle.  The  pipes  sometimes  had  the  shape  of  the  curved  butt 
of  a  pistol,  and  were  then  known  as  pistol-pipe  stoves.  In  using 
preheated  air  (hot  blast),  the  temperature  is  sometimes  regulated 
by  leveling,  i.e.,  admitting  a  certain  proportion  of  cold  air  to  the 
blast  when  a  fresh  stove  is  put  on,  and  then  gradually  cutting  it 
down  .to  nothing  by  the  time  the  stove  is  taken  off.  A  device 
suggested,  called  an  equalizer,  resembles  a  fire-brick  stove,  except 
it  is  used  continuously,  the  fire-brick  on  the  inside  serving  to 
absorb  heat  from  the  blast  if  it  is  too  hot,  and  give  it  up  again  if 
the  blast  is  too  cold,  thus  keeping  the  temperature  nearly  con- 
stant. To  remove  the  moisture  in  the  blast,  and  so  get  greater 
efficiency  from  the  furnace,  the  blast,  before  going  to  the  stoves, 
may  be  passed  over  pipes  in  which  iced  brine  is  circulated,  and  on 
which  the  moisture  is  deposited  as  ice :  this  constitutes  the  Gay- 
ley  dry  blast  process. 

Operation. — The  charge,  consisting  of  ore,  coke,  and  lime- 
stone (coal  or  charcoal  rarely  replace  the  coke),  is  put  in  at  the 
top  of  the  furnace,  at  nearly  regular  intervals,  the  operation  being 
continuous.  The  ratio  which  the  ore  bears  to  the  total  charge  is 
known  as  the  burden  (ore  burden).  If  this  ratio  is  too  great  or 
too  small  the  furnace  is  said  to  t>e  overburdened  or  underbur- 
dened  respectively.  With  ordinary  ore,  containing  about  50%  of 
iron,  the  proportions  of  materials  entering  and  leaving  the  fur- 
nace, based  on  one  ton  of  pig  iron  produced,  are  approximately 
as  follows,  expressed  in  tons : 


Materials  entering 

the  furnace 

Materials  leaving  the  furnace 

Ore 

2 

Pig  iron     i 

Coke 

j 

Slag  .                      H 

Gases   6 

Air 

Total  

Total                         7/^ 

BLAST  FURNACE  35 

It  will  be  noted  that  the  air  constitutes  over  one-half  of  all  the 
materials  going  into  the  furnace,  while  the  escaping  gases  repre- 
sent over  three-quarters  of  the  material  leaving  the  furnace.  This 
difference  is  due  to  the  fact  that  the  oxygen,  carbon  and  certain 
other  substances  which  enter  the  furnace  as  solids  are  converted 
into  the  gaseous  state  by  chemical  reactions  which  they  undergo. 
The  height  of  the  materials  in  the  furnace  is  maintained  at  a 
constant  level  called  the  stock  line.  This  is  determined  either  by 
thrusting  a  rod  through  a  hole  in  the  top  by  hand,  or  by  an  auto- 
matic device  (stock  indicator)  consisting  essentially  of  a  rod  con- 
nected to  a  wire  which  passes  over  a  pulley  and  leads  to  a  dial  or 
other  device  on  the  ground.  The  blast  entering  the  furnace  near 
the  bottom  burns  the  fuel  which  supplies  the  heat  as  well  as  the 
carbon  necessary  for  the  reduction  (deoxidation)  and  carburiza- 
tion  of  the  ore,  at  the  same  time  rendering  it  and  the  slag  molten. 
If,  owing  to  improper  working,  the  materials  become  pasty  (gob- 
bing up  or  engorgement),  they  may  then  (a)  stick  to  the  sides 
forming  a  ring,  (b)  arch  across  producing  a  scaffold  or  bridge,  or 
(c)  form  a  large  mass  called  a  skull,  thereby  preventing  the  descent 
of  the  charge  above,  and  the  furnace  is  then  said  to  be  hanging. 
When  this  obstruction  gives  way,  allowing  the  superincumbent 
mass  to  fall,  it  is  called  a  slip.  Attempts  to  break  down  (blow 
down)  the  scaffold  may  be  made  by  alternately  decreasing  and 
increasing  the  pressure  of  the  blast  (jumping)  or  also  by  increas- 
ing the  temperature  (coddling).  To  bring  down  a  scaffold  and 
other  obstructions,  a  torpedo  (blast  furnace  torpedo),  containing 
an  explosive,  may  be  introduced  through  one  of  the  tuyeres  or 
through  a  hole  cut  in  the  wall  of  the  furnace  and  discharged. 
Sometimes  there  seems  to  be  too  much  lime  on  the  furnace  for 
the  given  condition,  and  still  it  is  showing  a  lean  cinder  (slag  low 
in  lime) ;  this  is  what  is  commonly  termed  not  working  her  lime, 
and  is  caused  by  a  high  fusion  zone  accompanied  by  a  cold  bot- 
tom and  high  top  heat  (Imhoff).  On  the  other  hand  a  slip  will 
often  bring  down  too  much  limestone  so  that  it  will  cause  the  slag 
to  be  infusible  or  pasty;  this  is  known  as  a  lime  set.  If  the  heat 
generated  within  the  furnace  is  not  sufficient,  the  furnace  is 
working  cold,  and  may  result  in  scaffolds  (cold  scaffold,  cold 
hanging),  which  may  also  be  occasioned  by  the  furnace  working 
hot  (too  hot),  called  hot  scaffold  or  hot  hanging.  When  the 
charge  is  composed  of  materials  of  such  a  size  and  nature  that  the 
blast  passes  through  them  (they  are  said  to  take  the  blast) 
easily;  the  charge  is  open.  -On  the  other  hand,  when  the  blast 
does  not  ascend  uniformly,  the  condition  is  called  blast  wander- 
ing. The  action  of  the  charge  in  opening  up  irregular  openings 
for  the  blast  is  known  as  channeling,  a  term  also  sometimes  ap- 
plied to  the  abrasive  action  of  the  charge  on  the  furnace  walls 
giving  rise  to  grooves  or  channels.  If  the  penetration  of  the  blast, 
in  the  region  of  the  tuyeres,  is  insufficient,  it  is  likely  to  cause 
pillaring,  a  condition  where  there  is  a  pillar  of  cold  stock  extend- 
ing up  through  the  middle  of  the  hearth  and  surrounded  by  an 
annular  column  of  activity.  When  a  portion  of  the  wall  of  the 
furnace,  above  the  water-cooled  part,  becomes  unduly  heated, 


36  BLAST  FURNACE 

with  the  danger  of  burning  through,  the  furnace  has  a  hot  jacket 
or  hot  spot.  Depending  upon  the  reactions  taking  place  in 
different  regions  or  zones  of  the  furnace,  they  are  called  zone  of 
heat  interception,  near  the  top;  farther  down,  zone  of  carbon 
deposition;  still  lower,  zone  of  incipient  fusion;  then  zone  of 
slag  formation;  and,  at  the  tuyeres,  zone  of  complete  fusion. 
»  In  practice  there  are  four  important  reactions  which  may  be 
given  as  follows: 

(1)  Oxidation  of  coke: 

c  +  o  =  co 

(2)  Reduction  of  iron  ore: 

FexOy  +  yCO  =  xFe  +  yCO2 

(3)  Decomposition  of  CO2  in  one  or  more  ways.  e.g. : 

C02  +  C  =  2CO 

(4)  Decomposition  of  CO: 

2  CO  =  C  +  C02  - 

(4)  Can  proceed  only  where  the  temperature  lies  between  400° 
and  600°  C.  (750°  and  1110°  F.) ;  above  600°  C.  (1110°  F.)  it  pro- 
ceeds with  great  slowness  (Mathesius).  The  heat  balance  of  a 
blast  furnace  is  an  analysis  and  statement  showing  the  amount 
and  sources  of  heat  entering  the  furnace  either  as  sensible  heat 
in  the  blast,  etc.,  or  what  is  generated  within  by  the  combustion 
of  fuel;  this  must  of  course  equal  the  amount  of  heat  leaving  the 
furnace  in  different  forms  (sensible  or  latent)  in  the  gases,  slag 
and  iron,  and  by  radiation  through  the  furnace  walls. 

Casting. — The  cinder  is  tapped  out  at  more  frequent  intervals 
than  the  iron  (it  has  been  suggested  to  tap  the  iron  out  continu- 
ously by  a  syphon-like  arrangement),  those  before  the  tapping 
of  the  iron  being  called  flushes.  The  operation  of  tapping  the 
iron  is  usually  known  as  casting,  and  the  yield  of  iron,  the  cast. 
If  part  of  the  iron  does  not  come  out  readily,  it  is  said  to  lie 
back.  When  the  hearth  is  nearly  empty,  part  of  the  blast  escapes 
with  a  roaring  sound,  and  the  furnace  blows.  The  iron  is  led 
through  troughs  or  runners  to  the  pig  beds  if  it  is  to  be  sand  cast 
(see  page  342),  or  into  ladles  if  the  metal  is  to  be  used  direct  in  the 
molten  condition  (direct  metal),  or  is  to  be  cast  into  pigs  in  a  pig 
machine.  The  small  amount  of  slag  which  comes  out  of  the  iron 
notch  is  separated  from  the  iron  by  means  of  a  depression  in  the 
main  runner,  near  the  furnace,  called  the  skimmer,  the  iron  here 
flowing  under  a  clay- washed  cast-iron  plate  or  bridge  set  verti- 
cally, the  slag  which  is  much  lighter  being  backed  up  and  flowing 
off  at  one  side.  The  iron  from  the  main  runner  is  prevented  from 
entering  the  side  runners,  until  desired,  by  shutters,  which  are 
implements  of  cast  iron  washed  with  clay,  shaped  like  a  spade 
with  a  rod  cast  in  them  for  a  handle,  and  which  are  thrust  down 
into  the  junction  of  the  two  runners.  (For  the  method  of  han- 
dling the  iron  and  the  slag,  see  Pig  Machine  and  Slag  Machine.) 
The  cinder  notch  is  opened  up  by  a  pointed  bar,  and  closed  by 
holding  another  bar,  with  an  enlarged  end,  in  the  hole  until  the 
cinder  chills  against  it.  The  iron  notch  is  opened  by  drilling  out 


BLAST  FURNACE  37 

the  clay  with  which  it  is  closed,  and  finally  driving  in  a  pointed 
bar.  It  is  closed  by  slackening  the  blast,  and  then  packing  in 
balls  of  clay,  either  by  hand  with  bars,  or  by  a  machine  called  a 
gun,  notch  gun,  or  blast  furnace  gun.  This  machine  consists  of 
two  cylinders  tandem,  each  containing  a  piston  on  the  same  rod, 
the  first  being  actuated  by  steam  or  compressed  air,  and  the 
second  serving  to  drive  the  balls  of  clay,  which  are  thrown  in  at 
a  hole  in  the  top  of  the  cylinder. 

When  a  furnace  is  started  up  it  is  said  to  be  blown  in,  and 
when  it  is  taken  out  of  commission  it  is  blown  out.  Where  the 
operation  is  stopped  temporarily  by  taking  off  (stopping)  the 
blast  and  closing  up  all  the  openings,  it  is  banked  (damped  down) ; 


PIG.  7. — Blast  furnace  casting. 

when  operating,  it  is  in  blast.  The  methods  employed  for  blow- 
ing in  a  furnace  may  differ  in  certain  details,  but  the  following 
description  covers  the  general  practice  (sometimes  referred  to  as 
scaffolding  down).  A  wooden  scaffold  is  erected  inside  the  fur- 
nace at  a  height  a  little  above  the  level  of  the  tuyeres.  On  this  is 
piled  on  end  one  or  more  tiers  of  cordwood.  The  hearth  is  then 
filled  with  coke  up  to  about  the  bottom  of  the  tuyeres,  and  the 
space  between  this  and  the  scaffold  is  filled  in  with  thoroughly 
dried  kindling  wood  in  order  to-  ignite  the  mass  from  the  outside 
through  one  of  the  tuyeres.  A  considerable  amount  of  coke  is 
dumped  in  at  the  top  of  the  furnace,  the  last  portion  being  mixed 
with  some  finely  broken  clay  which,  when  melted,  serves  to  warm 
up  the  tapping  holes.  Very  little  ore  and  flux  are  added  for  some 
time,  the  proportion  being  increased  gradually  until  the  full 
burden  is  reached  after  a  day  or  two.  After  a  furnace  is  blown 


8  BLAST  FURNACE 

out,  accretions  (scars)  may  be  found  on  the  walls,  consisting  of 
partially  fused  matter  and  pieces  of  coke,  limestone,  etc.  In  the 
hearth,  usually  where  the  bottom  has  been  worn  away,  may  be 
found  a  metallic  mass,  called  a  salamander  (q.v.)  or  bear,  which 
consists  of  pig  iron  containing  nitrocyanide  of  titanium,  and  usu- 
ally also  there  is  iron  with  less  carbon  and  silicon  than  in  the 
regular  pig  iron.  Under  the  superintendent,  the  operations  are 
conducted  by  a  blower  who  has  general  charge  of  one  or  more 
furnaces,  the  hot  blastman  who  has  charge  of  the  stoves,  and  the 
keeper  who  attends  to  tapping  the  furnace  and  getting  the  run- 
ners, molds,  etc.,  in  shape. 


PIG.  8. — Blast  furnace  casting — Running  the  molten  pig  iron  into 
ladles  for  use  as  direct  metal. 


J.  E.  Johnson's  Process  is  a  method  of  spheroidizing  graphite 

in  cast  iron.  This  is  effected  "by  bessemerizing  the  iron  at  a 
relatively  low  temperature,  and  thus  removing  its  silicon  with  but 
little  removal  of  carbon  but  with  important  absorption  of  oxy- 
gen. The  graphite  of  the  resultant  produce  assembles  in  large 
part  in  relatively  harmless  spheroids,  instead  of  spreading  out  as 
usual  into  broad  continuity  destroying  flakes.  He  then  remelts 
his  iron,  adding  enough  silicon  to  bring  about  the  degree  of  graph- 
itization  desired  in  the  castings  themselves.  The  spheroidizing 
tendency  persists  through  this  remelting,  so  that  the  graphite  in 
the  resulting  castings  also  is  in  compact  masses"  (Howe). 


BLAST  FURNACE  COKE— BLOCK  FURNACE   39 

Classification   of   Furnaces. — According    to    the  methods  of 
operating: 

I.  Fuel  used: 

(a)  Coke  furnace. 
(6)  Charcoal  furnace. 

(c)  Anthracite  furnace  (a  certain  proportion  of  the  fuel  is 
coke). 

(d)  Coal  furnace  (Scotland  only). 
II.  Blast: 

(e)  Hot  blast  furnace. 
(/)  Cold  blast  furnace. 

III.  Charging: 

(g)  Barrow  charging  (hand). 

(h)  Skip  charging  (mechanically). 
Merchant  furnaces  are  those  whose  product  is  for  sale. 

Blast  Furnace  Coke. — See  page  96. 

Blast  Furnace  Gas. — See  page  33 . 

Blast  Furnace  Gun. — See  page  37. 

Blast  Furnace  Lining. — See  page  27. 

Blast  Furnace  Reactions. — See  page  36. 

Blast  Furnace  Slag  Cement.— See  Slag  Cement. 

Blast  Furnace  Torpedo. — See  page  35. 

Blast  Temperature. — See  page  28. 

Blast  Wandering. — See  page  35. 

Blau  Furnace;  Blauofen. — See  page  135. 

Blazed  Pig.— See  page  343. 

Blazing  off. — See  page  231. 

Bleckley  Mill.— See  page  417. 

Bled  Ingot. — See  page  58. 

Bleeder. — See  page  34. 

Bleeding. — (i)  Of  ingots  which  have  not  entirely  solidified,  so  that 
when  they  are  rolled  or  forged,  the  solid  skin  is  broken  and  the 
fluid  portion  forced  out;  (2)  in  a  furnace  lined  with  cinder,  melting 
or  fluxing  out  a  part  of  the  lining  when  it  becomes  too  thick,  by 
raising  the  temperature;  (3)  in  puddling:  see  page  377;  (4)  red 
streaks  of  rust  on  boiler  scale,  indicating  corrosion  in  the  metal 
underneath. 

Blending. — Mixing  ores  to  get  a  suitable  composition. 

Blind  Pass. — See  page  405. 

Blind  Tuyere. — See  page  17. 

Blister. — (i)  In  cemented  steel;  see  page  71;  (2)  suggested  as  a 
shorter  term  for  blister  bar  or  blister  steel;  (3)  an  excrescence  on 
the  surface  of  steel  produced  by  a  gas  bubble  present  or  found 
beneath  the  surface  while  the  metal  is  hot  and  plastic;  very  fine 
blisters  are  called  pinhead  or  pepper  blisters. 

Blister  Bar,  Metal,  Steel.— See  page  71. 

Block. — (i)  An  ingot  (rare);  (2)  the  solid  brick-work  surrounding 
the  port  of  a  regenerative  furnace;  (3)  a  revolving  drum,  slightly 
tapered  from  bottom  to  top,  for  drawing  wire  through  the  die, 
and  on  which  it  is  wound:  see  page  508. 

Block  Furnace.— See  page  134. 


40  BLOCK  MOVEMENT— BODY  IRON 

Block  Movement. — See  page  281. 

Block  Oven. — See  pages  95  and  134. 

Blomary  (obs.). — Bloomary:  see  page  134. 

Blood -red  Heat. — Temperature  color:  see  page  210. 

Bloodstone. — See  page  243. 

Bloom. — See  pages  135  and  411. 

Bloom  Steel  (Eng.). — Steel  rolled  into  blooms. 

Bloomary ;  Bloomery ;  Bloomary  Process. — See  page  134. 

Blooming  Mill;  Rolls. — See  page  411. 

Blow. — (i)  To  force  air  into  or  through;  (2)  of  a  blast  furnace:  see 
page  36;  (3)  of  castings:  see  page  55. 

Blow  Cold. — See  page  20. 

Blow  Down. — (i)  In  Bessemer  practice:  see  page  21;  (2)  in  blast 
furnace  practice:  see  page  35. 

Blow  Full;  Hot. — See  page  20. 

Blow  In ;  Blow  Out. — Of  a  blast  furnace:  see  page  37. 

Blow  Young. — See  page  21. 

Blower. — (i)  In  Bessemer  practice:  see  page  16;  (2)  of  a  blast  fur- 
nace: see  page  38;  (3)  a  defective  tube:  see  page  492. 

Blowers'  Glasses. — See  page  20. 

Blowhole. — See  page  55. 

Blowing  Engines. — Those  for  compressing  the  air  for  the  blast  used 
in  blast  furnaces,  Bessemer  converters,  etc.,  are  of  two  general 
types;  (a)  either  steam  or  gas-driven  reciprocating  engines,  or 
(6)  turbine-driven  rotary  engines  (turbo-blowers).  The  air  is 
sucked  into  and  compressed  in  cylinders  (blowing  tubs),  and 
passes  thence  into  the  blast  main. 

Blowing  Tub. — See  Blowing  Engine 

Blowing  Up.— See  Water  Gas. 

Blown. — Of  a  casting:  see  page  55. 

Blown  Metal. — See  page  18. 

Blowy. — Of  a  casting:  see  page  55. 

Blue  Annealing. — See  page  431. 

Blue  Billy. — See  page  245. 

Blue  Furnace;  Oven. — See  page  135. 

Blue  Iron  Earth. — See  page  244. 

Blue  Powder. — See  page  371. 

Blue  Short;  Shortness. — See  pages  46  and  198. 

Blue  Stone. — Commercial  sulphate  of  copper. 

Blue  Temper. — See  page  230. 

Blue  Vitriol. — Commercial  sulphate  of  copper. 

Blue  Working. — See  Hardness. 

Blueing. — See  page  367. 

Blume. — See  page  147. 

Bob. — Tup  or  drop  weight:  see  page  481. 

Bod. — See  page  182. 

Body. — (i)  Quality  and  uniformity  to  yield  easy  and  proper 
working;  (2)  consistency  or  density,  as  in  paints,  etc.:  see  page 
365;  (slof  a  converter:  see  page  17;  (4)  of  a  roll:  see  page  403. 

Body  Core. — See  page  299. 

Body  Force. — See  page  331. 

Body  Iron  (Eng.). — Of  wrought  iron,  especially  Swedish,  considered 


BOECKER  MILL— BOTTOM-FED  TUYERES         41 

of  special  suitability  for  manufacturing  into  crucible  steel 
(Brearly). 

Boecker  Mill. — See  page  417. 

Bog  Iron  Ore ;  Bog  Ore. — See  page  244. 

Bogey  Casting.— See  page  57. 

Bogie ;  Bogey. — Same  as  Buggy;  a  flat  car  or  wagon  usually  running 
on  a  narrow-gage  track. 

Bohemian  Process. — See  page  76. 

Boil. — (i)  In  Bessemer  practice:  see  page  20;  (2)  in  open  hearth 
practice:  se.e  page  314;  (3)  in  puddling:  see  page  376. 

Boiled  Bar  (obs.). — Common  puddled  bar. 

Boiler  Compound. — See  page  366. 

Boiling. — See  page  202. 

Boilings. — See  pages  377  and  438. 

Boiling  Point. — See  page  202. 

Boiling  Process  (obs.). — Puddling  Process  (q.v.). 

Bolometer. — See  page  207. 

Bolting. — See  page  408. 

Bolting-down  Rolls  (Eng.).— See  page  414. 

Bond. — See  page  86. 

Bone  (Eng.). — A  hard  streak  in  a  piece  of  steel  which  is  being  rolled 
or  forged,  produced  by  uneven  heating. 

Bone  Ash ;  Dust.— See  page  68. 

Bone  Phosphate  of  Iron. — A  material  sometimes  added  to  a  blast 
furnace  charge  when  it  is  desired  to  increase  the  content  of  phos- 
phorus in  the  pig,  e.g.,  for  certain  castings.  It  is  usually  con- 
sidered that  2.18  parts  are  equivalent  to  i  part  of  P2O5. 

Bonehill  Process. — See  page  380. 

Bontempi  Process. — See  page  368. 

Bookwalter  Converter. — Another  name  for  the  Robert  converter: 
see  page  24. 

Boot. — Of  a  bloomary:  see  page  135. 

Borax.— See  Flux. 

Boreas  Steel. — A  trade  name  given  to  an  early  grade  of  self-harden- 
ing steel. 

Borchers  Furnace.— See  page  154. 

Bordered  Boundary. — See  page  128. 

Boring  Gases  (Howe). — Those  obtained  on  boring  cold  solidified 
metal  under  water. 

Boron. — B;  at  wt.,  n;  sp.  gr.,  amorphous,  2.45,  crystalline,  2.53  to 
2.68.  Occurs  combined,  and  is  not  of  importance  as  a  constituent 
of  steel:  see  page  453. 

Boron  Steels.— See  page  453. 

Bosh. — See  page  27. 

Bot;  Bott;  Bot  Stick;  Botting  Up.— See  page  182. 

Bottling. — See  page  336. 

Bottom. — Of  a  converter:  see  page  17. 

Bottom-blown  Converter. — See  page  18. 

Bottom  Board. — In  molding:  see  page  297. 

Bottom  Casting, — See  page  57. 

Bottom  Cut ;  Discard.— See  Discard. 

Bottom-fed  Tuyeres.— See  page  31. 


42          BOTTOM  PART— BREAKER 

Bottom  Part.— Of  a  mold:  see  page  297. 

Bottom  Plate. — Of  a  converter:  see  page  17;  (2)  of  a  bloomary: 

see  page  135;  (3)  the  plate  on  which  an  open-bottom  mold  stands, 

usually  called  stool. 

Bottom  Pouring. — See  pages  57  and  299. 
Bottom  Pouring  Ladle. — See  Ladle. 
Bottom  Stuff.— See  page  17. 
Boucher  Process. — See  page  166. 
Bouiniard  Process. — See  page  317. 
Boullet  Process. — See  page  71. 
Boulton  Process. — See  page  61. 
Boundary  Edging. — See  page  128. 
Boundary  Filling;  Strength. — See  page  282. 
Bower  Process. — See  page  367. 
Bower-Barff  Process. — See  page  367. 
Bowke  (Eng.). — A  South  Staffordshire  term  meaning  a  small  wooden 

box  in  which  iron  ore  is  hauled  underground  (Raymond). 
Box. — (i)  An  iron  receptacle  for  holding  small  material,  and  usually 

handled  by  a  crane;  (2)  a  charging  box:  see  page  314;  (3)  the  nut 

or  hole  with  female  thread  in  a   housing,  through    which    the 

screw    turns. 

Box  Annealing. — See  pages  232  and  431. 
Box  Groove;  Pass. — See  page  405. 
Box  Piling.— See  page  378. 
Boydell  Process. — See  page  73. 
Boyle's  Law.— See  Gas. 
Boys  Radiation  Pyrometer. — See  page  207. 
Brake  Burns. — See  Crack. 
Brake  Test.— See  page  483. 
Branch  Core. — See  page  299. 
Branding. — See  Marking. 
Branning  Machine. — See  page  432. 
Brasque. — To  line  with  some  inactive  or  harmless  material,  or  one 

which  will  not  interfere  with  a  given  operation,  e.g.,  to  brasque 

a  clay  crucible  with  charcoal  or  lampblack. 
Brasses. — (i)  The  boxes  made  of  brass  or  bronze  containing  the 

babbitt  or  other  bearing  metal  on  which  the  necks  or  journals  of  a 

roll,  etc.,  turn.     Bushing  metal  is  the  name  sometimes  given  to 

an  alloy  of  copper  and  tin  (bronze)  used  for  this  purpose;  (2) 

pyrites  in  coal  (Eng.  and  Welsh). 
Bray  Continuous  Sheet  Mill. — See  page  433. 
Braze.— See  page  505. 
Break.— See    Curve. 
Break  Down. — (i)  Of  ingots,  etc.,  to  reduce  the  section  by  rolling  or 

forging,  more  particularly,   the  preliminary  operation;   (2)   of 

equipment  which  fails  under  load. 
Break  Out;  Through. — (i)  Of  the  flame  in  the  Bessemer  process, 

when  the  carbon  begins  to  burn:  see  page  20;  (2)    of   molten 

metal  which  forces  its  way  through  a  furnace  wall. 
Breaker. — (i)  A  machine  for  breaking  up  the  sow  and  pigs:  see 

Pig  Breaker;  (2)  in  coal  mining,  the  building  and  machinery  where 


BREAKING— BRIQUETTE  43 

the  coal  is  crushed  to  obtain  the  desired  size,  and  also  where  the 
slate  is  picked  out. 

Breaking. — See  page  330. 

Breaking-down  Point.— See  page  334. 

Breaking-down  Rolls. — See  page  414. 

Breaking-down  Temperature. — For  ordinary  tool  steel:  see  page 
446. 

Breaking  Load. — See  pages  336  and  471. 

Breaking  Spindle. — See  page  407. 

Breaking  Stress. — See  page  336. 

Breaking-up  Process. — See  page  75. 

Breast. — (i)  Of  a  Bessemer  converter:  see  page  18;  (2)  the  front 
bank  of  an  open  hearth  furnace;  (3)  that  side  of  the  hearth  of  a 
shaft  furnace  which  contains  the  metal  notch  (Raymond). 

Breast  Hole;  Plate. — See  page  182. 

Breccia;  Breccia  Structure. — See  page  125. 

Breeches  Runner. — See  page  57. 

Breeze. — Coke  breeze:  see  Coke. 

Breeze  Oven. — An  oven  in  which  breeze  (fine  coal  or  coke)  is 
burned. 

Breuil  Test.— See  page  482. 

Brick  Kiln;  Oven. — See  page  182. 

Bridge. — (i)  In  a  blast  furnace:  see  page  35;  (2)  in  a  reverbera- 
tory  furnace:  see  page  183. 

Bridge  Wall. — See  pages  183  and  375. 

Bright  Annealed  Wire. — See  page  509. 

Bright  Blue  Temper. — Oxide  color:  see  page  230. 

Bright  Crystalline  Fracture. — See  page  178. 

Bright  Finished  Wire.— See  page  507. 

Bright  Fracture. — See  page  178. 

Brighten. — Of  fuel  in  a  blast  furnace,  etc.,  which  is  cool  (not  burn- 
ing well),  to  increase  the  temperature,  as  by  injecting  oil. 

Brilliant  Fracture. — See  page  178. 

Brimstone  Acid. — Made  by  dissolving  in  water  the  fumes  from 
burning  sulphur;  sulphurous  acid.  It  contains  no  arsenic. 

Brinell's  Formula. — For  hardness  number:  see  page  477- 

Brinell  Hardness;  Hardness  Number. — See  page  477- 

Brinell  Meter. — See  page  478. 

Brinell's  Notation. — For  critical  point:  see  page  265. 

Brinell  Refining  Process. — See  page  384. 

Brinell  Test. — For  hardness:  see  page  477. 

Brinell  and  Wahlberg  Test.— See  page  482. 

Bring  Down. — Of  metal  in  a  cupola,  etc.,  to  melt. 

Bring  to  Nature. — See  page  376. 

Bring  Up. — Or  fetch  up,  to  increase,  e.g.,  the  percentage  of  carbon: 
see  page  393- 

Briquette;  Briquetting  (Briket;  Briketting). — A  block  or  brick  (or 
the  method  of  production)  of  a  substance  not  of  itself  coherent 
enough,  and  to  correct  which  some  binding  material  is  used. 
Fine  substances  such  as  coal,  ore,  etc.,  are  cemented  together  by 
fusible  (caking)  coal,  pitch,  lime,  etc.  After  mixing,  the  mate- 
rial is  put  in  molds,  usually  under  considerable  pressure,  and  with 


44  BRIQUETTE 

or  without  the  application  of  heat.  The  briquettes  are  then 
taken  out,  and  dried,  etc.,  as  necessary.  Some  of  the  various 
processes  may  be  mentioned  briefly  as  follows : 

The  Schumacher  process  "consists  in  mixing  with  flue  dust  a 
small  amount  of  liquid  containing  some  such  material  as  magne- 
sium or  calcium  chloride  in  solution,  then  thoroughly  mixing  the 
flue  dust  to  produce  as  nearly  a  homogeneous  mass  as  possible, 
and  finally  passing  it  through  a  briquetting  press  capable  of 
producing  high  pressures  up  to  about  6800  pounds  per  square 
inch"  (Clark).  The  Scoria  process  "invloves  the  use  of  granu- 
lated blast  furnace  slag  and  lime  as  a  binder.  Magnetically 
concentrated  flue  dust,  thoroughly  mixed  with  the  binding 
agents,  is  pressed  (at  approximately  1500  pounds  per  square  inch) 
into  the  form  of  rectangular  bricks  and  then  subjected  to  the 
action  of  live  steam  for  several  hours"  (Clark).  The  Grondal 
process  "consists  in  forming  briquettes  of  moistened  flue  dust  (or 
fine  ore)  without  any  binder,  piling  these  briquettes  carefully  on 
small  platform  cars  and  running  the  cars  into  heating  ovens, 
where  the  briquettes  are  subjected  to  a  high  temperature  over  a 
considerable  period  of  time.  The  carbon  contained  in  the 
briquettes  is  burned  out,  causing  a  sintering  action  throughout 
the  briquette,  which  causes  the  formation  of  a  firm  yet  porous 
brick"  (Clark).  In  the  tunnel  kiln  process,  as  practised  at  one 
plant,  flue  dust  is  first  magnetically  concentrated  and  "the  con- 
centrate is  then  briquetted  in  a  press  exerting  a  pressure  of  about 
7000  pounds  per  square  inch,  and  the  briquettes  finally  treated 
by  passing  them  through  long  tunnel  kilns  in  which  they  are  sub- 
jected for  about  5  hours  to  a  temperature  rising  to  about  2400° 
F.  in  the  hottest  zone"  (Clark).  The  Weiss  process,  used  for 
briquetting  ore,  flue  dust,  and  also  metallic  borings  is  based  on 
the  use  of  lime  as  a  binder  in  conjunction  with  the  formation  of 
the  carbonate  by  the  introduction  of  CO2.  This  gas,  under  pres- 
sure is  caused  to  penetrate  the  bricks,  cold  at  the  beginning  and 
warm  at  the  end,  in  order  to  produce  a  firm  bond  of  calcium  car- 
bonate. The  Ronay  process  is  also  used  for  briquetting  borings, 
these  being  subjected  to  heavy  pressure,  gradually  applied,  to 
squeeze  put  the  contained  air;  no  binder  is  employed. 

Roasting,  sintering  or  clinkering  are  resorted  to  for  the  purpose 
of  obtaining  a  suitable  product  for  use  in  the  blast  furnace,  etc., 
by  partially  fusing  the  material  and  so  obtaining  it  in  coherent 
form.  In  the  Heberlein  pot  method,  or  Huntington-Heberlein 
pot  process,  "flue  dust  is  treated  by  first  thoroughly  mixing  it 
into  a  mass  as  nearly  homogeneous  as  may  be,  then  charging  the 
same  into  a  large  pot  shaped  somewhat  like  a  Bessemer  converter 
and  holding  several  tons  of  material.  The  material  is  ignited 
from  the  bottpm  and  a  draft  of  air  forced  up  through  from  the 
bottom.  The  air  supports  combustion  of  the  carbon  contained  in 
the  mass  and  the  ignition  gradually  progresses  upward.  The 
result  is  to  burn  out  the  carbon  and  to  sinter  the  contents  of  the 
pot  into  a  solid,  though  porous  mass.  When  the  sintering  action 
has  progressed  throughout  the  material,  the  pot  is  inverted  and 
the  mass  which  falls  out  of  the  pot  is  broken  into  pieces  small 


BRIQUETTED  BORINGS— BRITTLE  45 

enough  for  use  in  the  blast  furnace"  (Clark).  The Greenawalt 
process  ' 'involves  the  same  principle  of  roasting  or  sintering,  but 
differently  arranged  apparatus  is  used.  The  principal  difference 
is  that  the  draft  is  down  through  the  mass  of  material  to  be  heated 
rather  than  up"  (Clark).  In  the  Dwight  and  Lloyd  process  the 
fundamental  principle  is  the  same  as  in  other  roasting  processes. 
"The  essential  features  of  this  method  are  comprised  in  the  form 
of  apparatus  used.  The  draft  to  support  combustion  during  the 
sintering  process  is  downward,  but  instead  of  carrying  on  the 
action  in  large  pots,  it  is  carried  on  in  a  much  larger  number 
of  smaller  pans.  These  pans  are  joined  end  to  end  to  form 
a  continuous  conveyor"  (Clark).  The  rotary  kiln  process 
"which  may  be  termed  sintering,  but  which  perhaps  is  more 
clearly  expressed  as  nodulizing  or  clinkering,  consists  in  treatment 
of  flue  dust  (or  ore)  in  a  rotary  kiln  similar  to  that  used  in  the 
cement  industry  for  the  burning  of  cement  clinker.  Flue  dust 
without  preliminary  treatment  is  charged  into  the  upper  end 
of  an  inclined  kiln  in  which  a  high  temperature  is  maintained  by 
the  combustion  of  fuel  at  the  lower  end.  This  fuel  is  generally 
pulverized  coal,  blown  in  with  an  air  blast.  The  material  is 
conveyed  through  the  kiln  by  the  rotation  thereof  and  is  agitated 
thereby  while  subjected  to  the  high  temperature.  The  result 
is  to  sinter  the  flue  dust  and  to  cause  the  small  sintered  particles 
to  agglomerate  into  nodules  varying  in  size  from  an  eighth  of  an 
inch  to  an  inch  and  a  half  in  diameter  and  roughly  spherical  in 
shape.  These  nodules  are  porous  and  of  excellent  quality,  physic- 
ally and  otherwise,  for  use  in  a  blast  furnace"  (Clark).  The 
West  sintering  process  consists  of  a  furnace  with  a  movable 
bottom  on  which  a  block  of  the  material  is  built  as  fast  as  the  con- 
tinuous action  of  the  heat  will  agglomerate  or  stick  the  particles 
together.  The  material  can  be  delivered  to  the  furnace  in  several 
ways:  (i)  Letting  it  fall  from  the  roof  and  spreading  it  out  me- 
chanically to  form  a  thin  layer;  (2)  using  a  kind  of  injector 
operated  by  air,  and  moving  it  over  the  area;  (3)  using  a  type 
of  continuous  furnace  with  the  bottom  moving  slowly  along,  the 
dust  being  charged  in  definite  places.  After  the  block  is  built  up 
to  the  capacity  of  the  furnace,  it  is  withdrawn  and  the  sinter 
removed  by  a  crane,  and  then  broken  to  size  as  desired.  If  the 
breaking  is  done  while  the  mass  is  red  hot  there  will  be  the  mini- 
mum of  effort  and  cost  (West). 

Briquetted  Borings. — See  Briquette. 

Bristol  Gas  Pyrometer. — See  page  207. 

British  Formula. — For  quality:  see  page  340. 

British  Imperial  Wire  Gage.— See  page  188. 

British  Thermal  Unit. — See  page  199. 

British  Yield  Point. — See  page  471. 

Brittle ;  Brittleness. — See  also  page  331.  The  tendency  to  rupture 
under  shock  or  stress,  more  particularly  one  which  is  suddenly 
applied,  without  any  appreciable  elongation  or  reduction  of  area. 
It  is  the  opposite  of  toughness,  but  should  not  be  confused 
with  hardness,  as  the  latter  is  not  synonymous.  Mechanical 
brittleness  (Arnold)  is  where  a  piece  of  metal  snaps  off  on  any 


46         BRITTLE  FRACTURE— BUILT-UP  TUYERE 

attempt  to  bend  it.  Potential  or  vibratory  brittleness  (Arnold) 
is  where  metal  gives  excellent  tensile  tests,  will  bend  double 
readily  without  fracture,  but  is  nevertheless  very  liable  to  frac- 
ture suddenly  under  vibration  or  alternation  of  stress,  at  a  stress 
below  its  elastic  limit.  Intermittent  brittleness  (Le  Chatelier)  is 
where  either  brittleness  or  toughness  may  be  produced  according 
to  the  previous  treatment.  Stead's  brittleness  is  of  rare  occur- 
rence, and  is  produced  by  heating  very  low  carbon  steel  for  a  long 
time  (days)  to  between  500°  and  750°  C.  (930°  and  1380°  F.). 
The  crystals  become  large,  and  the  steel  loses  a  large  part  of  its 
strength  and  ductility.  Shortness  is  used  synonymously  with 
brittleness:  (a)  red  shortness  or  hot  shortness,  when  hot;  (b) 
cold  shortness,  when  cold;  (c)  blue  shortness,  brittleness  when 
cold,  due  to  working  at  about  a  blue  (temper  color)  heat,  say 
300°  C.  (5  70°  F.) .  Material  slightly  red  short  is  also  called  tender 
or  weak.  Slag  shortness  is  brittleness  due  to  slag  inclusions. 

Brittle  Fracture. — See  page  178. 

Brittle  Hardness.— See  page  452. 

Broad  Twin. — Seepage  125. 

Broken  Hardening. — See  page  228. 

Broken  Rails. — See  Rail  Failures. 

Brooman  Process. — See  page  71. 

Brown  Coal. — See  Coal. 

Brown  Hematite:  Iron  Ore. — See  page  244. 

Brown  Mill. — See  page  41 7- 

Brown  Ore. — See  page  244. 

Brown  Process. — See  page  385. 

Brown  (George)  Process. — See  page  114. 

Brown  (Henry)  Process. — See  page  71. 

Brown  Pyrometer. — See  page  207. 

Brown  and  Sharpe  Gage. — See  page  188. 

Browne  Process. — Pig  iron  is  refined  in  any  way,  and  alloys  of  iron 
rich  in  manganese  or  silicon  are  then  added. 

Brownhill  and  Smith  Mill. — See  page  417. 

Browning;  Browned  Steel. — See  page  368. 

Bubble. — Blister:  see  page  71. 

Bubbling  Process  (obs.). — (i)  Bessemer  process;  (2)  puddling 
process. 

Bucher  Process.— See  page  373. 

Buckle.— See  page  58. 

Buckled  Plate. — (i)  A  defect:  see  page  175;  (2)  plates  which  are 
slightly  dished  to  stiffen  and  strengthen  them  (Eng.). 

Buckshot  Cinder.— See  Slag. 

Buckwheat  Coal.— See  Coal. 

Budd  Process. — See  page  385. 

Buddie.— See  Ore. 

Buffing. — See  page  285. 

Buffington  Process. — See  page  368. 

Bug. — See  Ladle. 

Buggy. — A  flat  car  or  wagon  running  on  a  narrow-gage  track, 

Buggy  Casting— See  page  57- 

Built-up  Tuyere. — Seepage  19. 


BULK  MODULUS— BY-PRODUCT  COKE  47 

Bulk  Modulus.— See  page  335- 

Bull  Dog. — See  page  376. 

Bull  Head. — See  page  412. 

Bull  Ladle.— See  Ladle. 

Bull  Process. — (i)    Direct  process:  seepage  138;  (2)  purification 

process:  see  page  385. 
Bundle. — See  pages  94  and  507. 
Bundle  Iron  (rare). — Nail  rods  made  by  cutting  up  plates  in   a 

slitting  machine,  and  put  up  in  bundles. 
Bung. — See  page  1 14. 
Bunsen  Mill. — See  page  41 7- 
Burden,  Ore. — Of  a  blast  furnace:  see  page  34. 
Burden  Squeezer. — See  page  377. 
Burgess  Process. — See  page  166. 
Burke  Furnace. — See  page  154. 
Burkheiser  Process. — See  page  96. 
Burning. — (i)  Of  crucibles:  see  112;  (2)  combustion:  see  page  202; 

(3)  of  iron  or  steel:  see  page  226;  (4)    of  molds:    see  page  298; 

(5)    of  bricks:  see  page  395. 
Burning    in. — (i)  Casehardening:  see  page  67;   (2)  of    enamels: 

see  page  370. 

Burning  off. — In  tempering:  see  page  231. 
Burning  on;  Together. — Form  of  soldering:  see  page  65. 
Burning  Zone. — See  page  226. 
Burnishing. — See  page  285. 
Burnt  Lime. — See  pages  175  and  396. 
Burnt  Mine  (Eng.). — Roasted  iron  ore. 
Burnt  Ore. — In  malleablizing:  see  page  258. 
Bursting  Theory. — Of  rupture:  see  page  179. 
Bushel  (Busheling)  Bar;  Iron;  Furnace;  Scrap. — See  page  379. 
Bushing  Metal. — See  Brasses. 
Bustle  Pipe.— See  page  32. 
Bustling  (obs.). — See  page  74. 
Butt. — (i)  The  bottom  end  of  an  ingot,  etc.;  (2)     the  edge  or 

vertical  surface  of  a  plate  or  a  piece  of  skelp;  a  term  used  in  the 

manufacture  of  welded  pipe. 
Butt  Ingot. — A  short  ingot,  the  last  one  poured  from  a  heat,  for 

which  there  is  not  sufficient  steel  to  fill  the  mold. 
Butt  Weld.— See  page  502. 
Butt  Welded  Pipe ;  Butt  Welding.— See  page  489. 
Buzzing  (obs.). — See  page  74. 
By-product. — Not  the  chief  product;  secondary. 
By-product  Coke,  Oven,  Recovery.    See  page  96. 


C. — (i)  Chemical  symbol  for  carbon;  (2)  symbol  for  the  unit  of 
electric  current,  the  ampere;  (3)  Centigrade  scale:  see  page  204; 
(4)  indicating  a  falling  temperature:  see  page  205. 

Ca. — Chemical  symbol  for  calcium  (lime),  q.v. 

Cb. — Chemical  symbol  for  columbium:  see  page  84. 

Cd. — Chemical  symbol  for  cadmium:  see  page  84. 

Ce. — Chemical  symbol  for  cerium:  see  page  84. 

C/. — Nature  of  carbon:  see  page  278. 

Cl. — Chemical  symbol  for  chlorine:  see  page  84. 

Co. — Chemical  symbol  for  cobalt,  q.v, 

Cr. — Chemical  symbol  for  chromium,  q.v. 

Cs. — Chemical  symbol  for  caesium:  see  page  84. 

Cu. — Chemical  symbol  for  copper  (Latin,  cuprum),  q.v. 

C  to  C. — Center  to  center,  used  as  points  of  measurement  in  ma- 
chinery, etc. 

C.  D.— Cold  drawn. 

C.  H.  B. — Charcoal  hammered  bloom. 

C.  H.  No.    . — Charcoal  hammered  No.  i. 

C.  H.  No.     F. — Charcoal  hammered  No.  i  flange. 

C.  H.  No.     F.  B. — Charcoal  hammered  No.  i  fire  box. 

C.  H.  No.     F.  F.  B. — Charcoal  hammered  No.  i  flange  fire  box. 

C.  H.  No.     S.— Charcoal  hammered  No.  i  shell. 

C.  I. — Calorific  intensity:  see  page  203. 

C.  J. — Cold  junction  (of  a  couple) :  see  page  209. 

C.  No.  i.— Charcoal  No.  i. 

C.  No.  i  R.  H.— Charcoal  No.  i  reheated. 

C.  P. — (i)  Chemically  pure:  see  page  89;  (2)  calorific  power: 
see  page  203. 

C.  R.— Cold  rolled. 

Gabbling.— See  page  377. 

Cadinho  Furnace. — See  page  138. 

Cadmia. — See  Zinc. 

Caking  Coal.— See  Coal. 

Calcar.— See  page  181. 

Calcareous. — Limy. 

Calcareous  Ore. — See  page  243. 

Calcination. — Applying  heat  to  a  substance  to  drive  off  the  volatile 
matter,  usually  without  the  access  of  air;  roasting  is  the  same 
operation  with  access  of  air,  and  usually  at  a  higher  temperature, 
but  below  the  fusion  point.  Calcination  is  frequently  used  as  the 
name  for  both.  See  also  Ore. 

Calcining  Kiln. — A  kiln  for  calcining  or  roasting  ores,  limestone, 
etc.;  see  page  181. 

Calcite.— See  Flux. 

Calcium.— Ca;  at.  wt,  40;  melt,  pt.,  760°  C.  (1400°  F.);  sp.  gr.,  1.85. 
A  silvery  white  metal  moderately  soft  and  malleable.  Is  not 
found  free  in  nature  its  principal  occurrence  being'as  the  carbon- 

48 


CALCIUM— CAP  49 

ate,  limestone.  It  alloys  with  silicon,  and  this  material,  termed 
silico-calcium,  has  been  tried  as  a  deoxidizer  for  steel.  The 
element  is  sometimes  referred  to  as  lime,  e.g.,  carbonate  of  lime, 
instead  of  carbonate  of  calcium. 

Calcium. — Fluorspar:  see  Flux. 

Calcium  Chloride. — (i)  As  a  flux:  see  page  176;  (2)  in  hot  etching: 
see  page  287. 

Calcium  Fluoride.— See  Flux. 

Calebasse  (French). — A  crude  form  of  furnace,  used  in  place  of  a 
cupola,  for  melting  pig  iron  for  small  foundries.  It  consists  of  an 
upper  part  (la  tour)  removable  from  a  lower  part  (le  creuset), 
blast  being  supplied  by  a  single  tuyere.  There  is  no  tap  hole, 
the  bottom  part  serving  also  as  a  ladle. 

Calescence;  Calescence  Point. — See  page  265. 

Caliber;  Calibre. — (i)  The  diameter,  especially  the  inner  diameter 
or  bore;  (2)  also  used  as  a  measure  of  length,  especially  of  a  gun, 
in  terms  of  the  bore,  thus  an  8"  gun  50  calibers  long  would  have 
a  length  of  400"  or  33'  4". 

Calibration. — Of  a  testing  machine:  see  page  469. 

Calibre. — Same  as  caliber,  q.v. 

Californian  Furnace. — See  page  162. 

Calipers. — See  page  187. 

Callendar  Dish  Radio-balance. — See  page  207. 

Callendar  Gas  Pyrometer. — See  page  207. 

Callendar  &  Griffiths  Electrical  Resistance  Pyrometer.— See 
page  208. 

Callendar  Recording  Pyrometer. — See  page  210. 

Caloric. — See  page  199. 

Calorie. — See  page  199. 

Calorific  Agent. — See  page  200. 

Calorific  Intensity. — See  page  203. 

Calorific   Power. — See  page  203. 

Calorimeter. — Seepage  201. 

Calorimetric  Method. — Of  determining  critical  points:  see  page 
265. 

Calorimetric  Pyrometer. — See  page  207. 

Calorimetry. — See  page  201. 

Calorizing. — See  page  372. 

Calory  (obs.). — Calorie:  see  page  199. 

Cam  Squeezer. — See  page  377. 

Camber. — (i)  In  structural  shapes  and  rails,  the  vertical  curva- 
ture measured  by  the  versed  sine;  (2)  in  plates,  the  lateral 
curvature,  which  in  the  case  of  structural  material  or  rails  is 
called  sweep. 

Cambier  Converter. — See  page  23. 

Cammel's  Process. — See  page  9. 

Campbell's  Formulae. — For  tensile  strength:  see  page  338. 

Campbell  (H.  H.)  Process. — See  page  317. 

Cancellated  Structure. — See  page  126. 

Cannel  Coal.— See  Coal. 

Cantilever  Beam. — See  page  468. 

Cap. — To  close  the  top  of  an  ingot  mold  either  with  sand  and  an 
4 


50  CAPILLARY  STRUCTURE— CARBON 

iron  plate,  or  else  with  a  circular  cast-iron  or  steel  cap  which  fits 
in  a  corresponding  hole  in  the  top  of  the  mold;  to  stopper  down 
(Eng.). 

Capillary  Structure. — See  page  125. 

Car  Casting. — See  page  57. 

Carbide  Carbon. — See  page  273. 

Carbide  Steel. — See  page  443. 

Carbo-allotropic  Theory. — Of  hardening:  seepage  280. 

Carbon. — (i)  Influence  on  corrosion:  see  page  366;  (2)  as  a  re- 
fractory: see  page  398. 

Carbon. — C;  at.  wt.,  12;  sp.  gr.  diamond.  3.5;  graphite,  2.5; 
gas  carbon,  2.35;  charcoal,  1.57.  Carbon  occurs  as  three  allo- 
tropic  varieties:  the  diamond,  which  is  crystalline  and  color- 
less or  colored,  occurring  naturally,  and  rarely  obtained  in 
an  electric  furnace;  graphite,  which  occurs  naturally  in  black 
crystalline  plates,  or  may  be  prepared  artificially  in  an  electric 
furnace;  and  amorphous  carbon,  which  is  deposited  on  cool  sur- 
faces when  carbonaceous  matter  is  burned  with  an  insuffi- 
cient supply  of  air.  An  amorphous  form  of  graphite  has  been 
termed  graphitite;  a  natural  fuel,  containing  only  traces  of 
oxygen  and  hydrogen,  has  been  called  schungite  or  graphitoid, 
and  it  has  been  suggested  that  this  name  be  used  for  fuels  inter- 
mediate between  graphite  and  anthracite.  The  par  bo  n  which 
separates  out  in  plates  from  cast  iron  during  solidification  is 
called  graphite  or  Irish.  A  substance  having  the  appearance 
of  graphite  is  sometimes  said  to  be  graphitoidal. 

Carbon  is  the  principal  constituent  of  all  common  fuels, 
either  solid,  liquid,  or  gaseous,  the  most  important  of  which 
are  coal  and  coke,  used  for  heating  and  reduction.  It  is  the 
most  important  constituent  of  iron  and  steel,  and  is  the  chief 
factor  in  making  its  varied  properties  and  conditions  possible. 
In  increasing  amounts  it  raises  the  strength  and  the  hardness, 
and  also  the  brittleness.  The  last  is  not  a  desirable  quality, 
but  carbon  causes  less  of  this,  combined  with  greater  strength, 
than  any  other  element.  This  statement  may  require  slight 
modification  in  the  case  of  some  special  steels.  With  increas- 
ing carbon  content,  the  elongation  and  the  reduction  of  area 
are  decreased.  With  carbon,  say,  over  0.30%,  iron  can  be 
hardened  by  rapid  cooling  from  above  the  critical  point. 

In  making  a  chemical  analysis  of  cast  iron  or  steel,  the  carbon 
is  reported  as  combined  carbon,  graphitic  carbon,  and  the  two 
together,  total  carbon.  Combined  carbon  is  that  which  is 
combined  directly  with  the  metal  or  is  dissolved  in  it,  for  which 
Howe  has  suggested  the  name  agraphitic  carbon.  Graphitic 
carbon,  graphite,  or  uncombined  carbon  is  that  which  is  simply 
mechanically  mixed  with  the  metal.  When  combined  carbon  is 
determined  volumetrically,  by  comparing  or  matching  the  colora- 
tion of  a  solution  of  the  sample  with  that  of  a  known  standard,  it 
is  termed  color  carbon,  to  indicate  the  method  employed  as 
distinguished  from  burning  the  carbon  in  oxygen  and  weighing 
the  carbonic  acid  produced,  called  carbon  by  combustion  or 
combustion  carbon.  Howe  uses  the  term  missing  carbon  to 


CARBON  ADDITIONS— CARBONATE  ORE  51 

denominate  that  portion  of  the  combined  carbon  in  rapidly  cooled 
steel  which  is  not  shown  by  a  color  determination.  The  change 
of  carbon  from  one  condition  to  another,  i.e.,  from  the  combined 
to  the  uncombined,  or  vice  versa,  is  sometimes  referred  to  as 
transcarburization. 

Carbon  forms  two  very  important  oxides  with  oxygen,  both 
of  which  are  gaseous  under  ordinary  conditions.  Carbon  dioxide, 
CO2,  also  called  carbonic  acid  or  carbonic  anhydride,  is  the  result 
of  the  complete  oxidation  (combustion)  of  carbon.  When  acted 
upon,  at  a  high  temperature,  by  additional  carbon,  it  is  partially 
reduced,  forming  carbon  monoxide,  CO,  also  termed  carbonic 
oxide  or  rarely  carbon  oxide  gas ;  this  reducing  action,  in  connec- 
tion with  solid  fuel,  being  rarely  called  carbon  transfer.  It  is 
valuable  as  a  reducing  agent  but,  in  the  case  of  iron,  the  action  is 
never  perfectly  complete.  Carbon  monoxide  acts  as  a  radical  to 
form  compounds  with  certain  elements,  and  is  then  termed 
carbonyl.  Iron  apparently  forms  two  such  compounds,  called 
ferro-carbonyl  or  iron  carbonyl,  Fe(CO)s  and  Fe2(CO)7,  when 
finely  divided  iron,  at  comparatively  low  temperatures,  is  allowed 
to  remain  in  contact  with  the  gas. 

Carbon  Additions. — See  Recarburization. 

Carbon  of  Annealing. — See  page  272. 

Carbon  Bloom. — See  page  138. 

Carbon  Brick. — See  page  398. 

Carbon  of  Cementation. — See  page  272. 

Carbon  Change. — A  change  in  the  condition  of  carbon  occurring 
in  iron  or  steel. 

Carbon  by  Combustion. — See  Carbon. 

Carbon  Core. — See  page  299. 

Carbon  Deposition,  Zone  of. — In  blast  furnace  practice:  see  page 
36. 

Carbon  Dioxide. — See  Carbon. 

Carbon  Free. — A  term  used  to  designate  metals  and  alloys  practi- 
cally free  from  carbon,  which  makes  them  more  suitable  for  cer- 
tain purposes. 

Carbon  Iron. — Iron  (either  steel  or  cast  iron)  in  which  carbon  is  the 
principal  constituent. 

Carbon  Iron  Company's  Process. — See  page  138. 

Carbon-iron  Diagram. — Iron-carbon  diagram:  see  page  271. 

Carbon  Monoxide. — See  Carbon. 

Carbon  of  Normal  Carbide. — See  page  272. 

Carbon  Oxide  Gas. — See  Carbon. 

Carbon  Steel. — See  page  443. 

Carbon  Theories. — Of  hardening:  see  page  279. 

Carbon  Tool  Steel. — See  page  445. 

Carbon  Transfer. — See  Carbon. 

Carbon  Value. — See  page  87. 

Carbonate. — (i)  The  combination  of  a  base  with  carbon  dioxide;  to 
convert  into  a  carbonate  or  to  impregnate  with  carbon  dioxide; 
(2)  (obs.)  to  carburize  or  carbonize:  see  Carburize;  (3)  see 
Carbonization. 

Carbonate  Ore. — See  page  244. 


52  CARBONIC  ACID— CAST  IRON 

Carbonic  Acid. — See  Carbon. 

Carbonic  Acid  Theory. — Of  corrosion:  see  page  107. 

Carbonic  Anhydride. — See  Carbon. 

Carbonic  Oxide. — See  Carbon. 

Carbonization. — (i)  Of  fuels,  coking  or  driving  off  the  volatile 

matter;  (2)  commonly  used  instead  of  carburization,  meaning 

impregnation  with  carbon:  see  pages  66  and  393. 
Carbonized  Iron. — Usually  a  pig  iron  rendered  brittle  by  excess  of 

silicon  (Raymond). 
Carbonizing  Process. — See  page  66. 
Carbonless. — A  term  used  to  designate  metals  and  alloys  practically 

free  from  carbon,  which  makes  them  more  suitable  for  certain 

purposes. 

Carbonyl. — See  Carbon. 
Carborundum. — (i)  As   a  silicon  addition:  see   Recarburization; 

(2)  as  a  refractory:  see  page  398. 
Carburet. — (i)  Carbide;  (2)  to  carburize  (rare). 

Carburite. — A,name  given  to  a  mixture  of  about  50%  each  of  car- 
bon and  iron,  used  for  recarburizing,  particularly  in  the  electric 
furnace. 

Carburize. — Also  termed  carbonize;  to  introduce  carbon  (i)  while 
steel  is  molten  by  adding  coke,  coal,  ferro-manganese,  etc.  (see 
Recarburization),  or  (2)  while  in  the  solid  state,  by  heating  it  in 
contact  with  carbonaceous  matter  below  its  melting  point 
(see  Cementation). 

Carburizing-fusion  Process. — See  page  113. 

Carburizing  Process. — See  page  66. 

Carburizing  Varnishes. — See  page  69. 

Carinthian  Process. — See  page  76. 

Garment's  Process. — Consists  in  piling,  reheating,  and  rolling 
steel  scrap  with  steel  or  iron  turnings. 

Camelry  &  Burton's  Pyrometer. — See  page  210. 

Caron's  Cement. — See  page  68. 

Caron's  Method. — Of  hardening:  see  page  229. 

Caron's  Process. — See  page  68. 

Carpenter  &  Reeling's  Equilibrium  Diagram. — See  page  272. 

Carrier. — See  page  406. 

Cascade  Furnace. — See  page  146. 

Case. — (i)  In  cementation:  see  page  67;  (2)  of  a  mold:  see 
page  297. 

Case  Carbonizing. — Case  hardening:  see  page  67. 

Case  Hardening. — See  page  66. 

Caspersson  Process. — See  page  60. 

Cast. — (i)  The  act  of  tapping  a  blast  furnace:  see  page  36;  (2) 
the  metal  taken  from  a  blast  furnace  at  regular  intervals; 

(3)  a  term  for  objects  which  are  produced  from  the  molten  state. 
Cast  House.— See  page  27. 

Cast  Iron. — (i)  In  general,  usually  called  pig  iron  (q.v.),  the 
product  obtained  by  reducing  iron  ore  or  similar  materials 
with  carbon  at  a  temperature  sufficiently  high  to  render  it 
fluid  (molten).  It  is  made  in  the  blast  furnace,  sometimes 


CAST  IRON  ARMOR  PLATE— CASTING  53 

in  the  electric  furnace,  and  occasionally  in  the  high  bloomary 
when  that  was  in  use.  It  contains  a  considerable  proportion 
of  carbon  (say,  2.20  up  to  about  7% — usually  from  about  2.5  to 
4%)  and  variable  percentages  of  other  substances,  such  as  silicon, 
manganese,  phosphorus,  sulphur,  etc.  It  is  hard  and  brittle,  and 

*  cannot  be  rolled  or  forged  at  any  temperature.  (2)  In  a  more 
restricted  sense  the  above  product  cast  in  its  final  form,  the  metal 
for  this  purpose  being  usually  first  cast  in  pigs,  and  subsequently 
remelted,  although  it  is  sometimes  used  in  the  molten  state  as  it 
comes  from  the  blast  furnace.  Cast  iron  is  defined  by  I.A.T.M. 
as  "Iron  containing  so  much  carbon  that  it  is  not  usefully 
malleable  at  any  temperature." 

Cast  Iron  Armor  Plate. — See  page  9. 

Cast  Iron  Mold. — See  page  296. 

Cast  Iron  Pipe. — See  page  489. 

Cast  Seam. — A  fin  formed  in  a  casting  when  the  mold  has  joints 
into  which  some  of  the  metal  runs. 

Cast  Steel. — (i)  Crucible  steel:  see  Crucible  Process;  (2)  any 
object  made  from  steel  in  the  molten  condition. 

Cast-welding  Process.— Pouring  molten  metal  between  objects  to 
be  welded  or  fastened  together. 

Casting. — (i)  The  operation  of  tapping  a  blast  furnace;  (2)  melting 
cast  iron  in  a  cupola  for  foundry  work  (obs.),  sometimes  called 
running  down ;  (3)  a  metal  object  which  receives  its  shape  from  a 
mold  (see  Molding)  into  which  the  metal  is  poured  while  in  a 
molten  condition  and  there  allowed  to  solidify;  (4)  the  operation 
of  filling  molds,  also  termed  teeming  or  pouring.  A  special  kind 
of  casting  known  as  ingots  is  the  form  in1  which  steel  is  cast 
for  subsequent  rolling  or  forging;  these  are  usually  rectangular, 
rarely  round  or  hexagonal,  in  cross  section;  if  more  than  twice 
as  wide  as  they  are  thick  they  are  termed  slab  ingots  ;  the  height 
is  usually  two  to  four  times  the  thickness  or  diameter.  Castings 
ordinarily  as  considered  may  be  annealed  or  machined,  or  both, 
but  do  not  receive  any  rolling  or  forging.  The  manufacture  of 
castings  is  sometimes  termed  founding ;  and  the  plant  or  shop 
where  they  are  made,  a  foundry. 

Piping. — During  the  solidification  of  any  casting,  the  action 
proceeds  inward  from  the  portion  in  contact  with  the  walls  of 
the  mold.  (In  this  connection  a  core  or  interior  division  of  a 
mold  is  to  be  considered  as  a  wall).  As  contraction  proceeds, 
since  the  metal  itself  is  of  smaller  bulk  when  solid  than  when 
molten,  eventually  a  longitudinal  cavity  is  left  near  the  top, 
where  solidification  last  occurs,  since  below  this  point  any  in- 
cipient cavity  is  immediately  filled  with  molten  metal.  This 
cavity  is  known  as  a  pipe  on  account  of  its  shape  (also  termed 
cavity,  contraction  cavity,  void,  vug,  sink  hole,  shrink  hole, 
draw  hole).  Liquid  contraction  is  that  which  occurs  up  to  the 
point  of  solidification;  used  by  Longmuir  in  connection  with  the 
formation  of  cavities  in  the  heavy  parts  of  castings  when  an 
outside  skin  had  formed.  Solid  contraction  occurs  after  solidifi- 
cation is  complete.  Howe  points  out  (Am.  I.  &  S.  List.,  1915)  that 
during  the  early  stages  of  solidification  the  exterior  cools  faster 


54 


CASTING 


than  the  interior  (pre-neutral  period),  at  some  moment  the  rates 
are  the  same  (neutral  moment),  and  afterwards  the  rates  are 
reversed  (post-neutral  period) ;  that  the  relative  rates  of  cooling 
of  the  different  portions  govern  the  piping.  The  exterior  or 
major  shrinkage  is  that  which  is  measured  by  the  external  di- 
mensions ;  the  interior  or  minor  shrinkage  is  that  which  occurs  in 
an  opposite  direction  in  the  interior  of  the  casting  tending  to  pro- 
duce a  pipe.  The  question  is  further  complicated  by  the  fact  that 
owing  to  variations  in  composition,  due  to  segregation  or  initial  het- 
erogeneity, the  solidification  does  not  usually  occur  at  a  single 
definite  temperature  but  over  a  range  (solidification  range) 
giving  rise  to  progressive  freezing. 


FIG.  9. — Pouring  a  heat  of  steel. 

To  facilitate  the  discussion  of  the  phenomena  of  progressive 
freezing,  H.  M.  Howe  adopted  provisionally  certain  terms  for 
which  he  has  given  the  following  definitions :  Frozen  continent, 
the  part  of  the  alloy  which  at  any  given  instant  under  considera- 
tion has  already  frozen;  shore  layers,  those  which  have  already 
in  part  solidified,  and  yet  in  part  remain  unfrozen  with  pool-lets 
or  estuaries  of  still  molten  matter,  or  in  other  words  the  layers  in 
which  freezing  is  actually  going  on;  littoral  region,  that  part  of 
the  still  unfrozen  alloy  immediately  adjoining  the  shore  layers,  in 
other  words,  the  layers  which  have  not  yet  actually  begun  freez- 
ing but  are  about  to;  open  sea,  the  still  unfrozen  mother  metal 
beyond  the  littoral  region.  Freezing,  during  which  pools  of 


CASTING  55 

metal  are  isolated  (which  he  terms  the  landlocking  type),  proceeds 
by  the  outshooting  of  pine-tree  crystals  (so-called  from  the  fan- 
cied resemblance;  also  arborescent  or  dendritic),  the  tangled 
branches  of  which  lock  up  much  of  the  impure  metal  of  the  littoral 
region,  and  thus  prevent  it  from  diffusing  centerward  or,  in  short, 
from  segregating.  But  in  the  onion-skin  type  the  successive 
deposition  of  smooth  concentric  layers  does  not  thus  obstruct 
the  centripetal  travel  of  the  impurities. 

Blowholes. — Metals  also  evolve  more  or  less  gas  during  solidi- 
fication, and  any  which  cannot  escape  is  mechanically  held  in 
little  pockets  called  blowholes  (sometimes  gas  holes)  which  are 
generally  arranged  symmetrically  to  the  axis.  * 

Those  occurring  near  the  surface  are  called  subcutaneous  or 
surface  blowholes ;  if  open  at  the  surface,  cutaneous  blowholes ; 
those  nearer  the  center,  deep-seated  blowhoies.  A  casting 


FIG.   10. — Ingot  broken  transversely  showing  subcutaneous 
blowholes. 

containing  an  excessive  number  of  blowholes,  rendering  it  un- 
sound, is  said  to  be  honeycombed,  porous,  blown,  blowy, 
spongy,  or  mushy ;  in  such  cases  the  blowholes  are  rarely  termed 
shrink  holes.  Since  the  space  occupied  by  any  blowholes  corre- 
sponds to  an  equal  amount  of  contraction  cavity,  it  is  evident 
that  where  there  are  many  blowholes  the  pipe  will  not  be  so 
extensive  as  where  they  are  absent;  in  other  words,  other  condi- 
tions being  similar,  the  space  occupied  by  the  blowholes  and  the 
pipe  is  equal  to  that  of  the  contraction  cavity.  Steel  from  which 
the  gases  have  been  removed  is  sometimes  referred  to  as  degasi- 
fied  steel;  it  is  correspondingly  free  from  blowholes  wnich 
necessarily  means  a  large  pipe,  hence  called  piping  steel.  Where 
the  steel  contains  much  gas  it  has  a  tendency  to  rise  in  the  molds 
(rising  steel)  and  the  resulting  casting  contains  rumerous  blow- 
holes, sometimes  termed  open  steel. 

Segregation  is  the  concentration  of  the  carbon  and  impurities 
(in  solution)  into  that  portion  of  a  metal  casting  which  solidifies 
last.  Liquation  is  also  used  in  the  same  sense,  but  Howe  suggests 
that  segregation  be  used  "to  designate  a  concentration  inward, 


56  CASTING 

and  liquation  an  expulsion  of  matter  outward  from  the  exterior 
of  the  mass,  but  without  insisting  on  the  propriety  of  the  termi- 
nology. The  metal  other  than  the  segregation  is  known  as  the 
mother  metal  (also  called  segregans) :  it  is  not  closely  analogous 
to  mother  liquor,  for  it  is  in  general  the  first  crystallized  and 
purer  substance,  the  segregation  being  the  residue  left  from  its 
crystallization,  while  mother  liquor  is  the  impure  residue  left  by  the 
early  formed,  relatively  pure  crystals."  The  term  segregate 
is  also  used  for  the  segregated  portion  expelled  in  the  freezing 
of  the  earlier  layers  and  usually  found  concentrated  in  the  axis  of 
the  ingot  (axial  segregate).  Segregation  was  the  term  used  by 
Kosman  (1903)  to  designate  the  separation  of  the  constituents  of 
an  alloy  by  partial  melting  (i.e.,  of  one  of  them) ;  in  its  usual  sense, 


PIG.   ii. — Ingot   broken  transversely   showing   deep-seated 
blowholes. 

as  described  above,  it  means  a  differentiation  or  purification 
(of  the  mother  metal).  Howe  introduced  the  terms  segregation 
excess  for  the  excess  of  the  percentage  of  an  element  in  the 
segregate  over  that  in  the  segregans,  and  segregation  deficit  or 
negative  segregation  for  the  opposite  condition  resulting  from  the 
impoverishment  of  certain  parts  to  provide  the  excess  found  in  the 
segregate. 

With  an  ordinary  casting  the  mold  is  made  to  provide  for  an 
excess  of  metal  above  the  casting  proper.  This  extra  metal 
serves  to  keep  the  body  of  the  mold  full,  and  to  receive  any  dirt  or 
scum  (suilage)  which  rises  (called  head  metai),  and  should  also  be 
large  enough  to  contain  all  the  pipe.  This  portion  of  the  casting 
is  called  the  sinkhead,  sinking  head,  shrinking  head,  settling 
head,  feeder,  feeding  head,  suilage  piece,  riser,  rising  head,  head, 
deadhead,  or  header ;  the  top  of  an  ordinary  ingot  is  rarely  called 
the  sand.  In  the  case  of  iron  molds,  if  a  lining  of  refractory 
material  is  used  around  the  sink  head,  to  retard  solidification  at 
that  point,  it  is  termed  a  hot-top  sink  head.  The  pressure 
resulting  from  the  height  of  metal,  as  in  the  sink  head,  is  some- 
times referred  to  as  ferrostatic  pressure,  similar  to  hydrostatic 
pressure  for  a  head  of  water.  If  the  rate  of  contraction  is  so  un- 
equal that  the  casting  is  distorted  from  casting  strains,  it  is  said 
to  be  warped  or  sprung ;  if  the  action  is  still  more  severe,  so  that  sur- 
face cracks  result,  it  is  termed  checking  or  pulling,  also  the  latter  if 


CASTING  57 

actual  rupture  results.  Siag  inclusions,  also  called  cinder  inclu- 
sions, dirt  inclusions,  or  simply  inclusions,  are  particles  of  slag  or 
dirt  occurring  in  the  metal  due  to  being  mechanically  held  so  they 
could  not  escape  to  the  top  before  solidification.  Casting  boil 
usually  refers  to  a  condition  in  blast  furnace  practice  where  the 
runners  are  damp  and  the  hot  metal  generates  steam  causing  ex- 
plosions; in  the  same  way  with  damp  molds,  particularly  sand 
molds,  dampness  leads  to  the  formation  of  steam  which  causes  a 
more  or  less  honeycombed  or  badly  pitted  surface  on  the  casting. 
Ingotism  is  the  name  applied  by  Howe  to  designate  the  very 
coarsely  granular  condition  of  certain  castings  poured  at  a  high 
temperature  and  slowly  cooled ;  this  structure  tends  to  persist  even 
after  annealing  or  other  heat  treatment  and  may  require  mechan- 
ical working  to  destroy  it.  During  the  cooling,  the  cohesion  be- 
tween adjacent  grains  may  not  be  sufficient  to  resist  the  con- 
traction strains,  so  that  there  is  a  partial  separation  between  them. 
Any  subsequent  heat  treatment  therefore  has  no  more  effect  in 
uniting  them  than  upon  two  pieces  simply  laid  against  each  other; 
mechanical  working  will  usually  effect  a  reunion  provided,  of 
course,  the  surfaces  are  free  from  oxide  or  dirt.  A  scorched  ingot 
(Eng.)  is  one  which  has  a  needle  structure  and  is  brittle,  perhaps 
clue  to  being  poured  too  hot. 

Pouring  or  Teeming. — The  metal  may  be  poured  directly  into 
the  top  of  the  mold  (top  pouring,  top  casting),  practically  always 
from  some  form  of  ladle  (q.v.),  but  this  method  is  generally 
restricted  to  iron  molds  for  ingots,  as  the  falling  metal  is  likely 
to  tear  and  destroy  (wash)  the  surface  of  sand  molds.  In  the 
latter  case  the  metal  is  introduced  through  a  hole  at  the  side  or 
bottom,  by  a  separate  channel  called  a  runner  which  connects 
with  the  mold  itself  by  a  gate,  the  metal  in  the  runner  is  also 
referred  to  by  the  same  name,  and  the  portion  in  the  gate  is  called 
the  runner  head.  This  method  is  known  as  bottom  pouring 
(casting)  or  ascensional  casting,  and  the  casting  itself  is  similarly 
designated,  sometimes  also  as  a  rising  casting.  In  filling  ladles 
from  a  furnace,  or  open  top  molds  from  a  ladle,  a  split  runner  may 
be  used  sometimes  called  a  breeches  runner,  to  permit  of  double 
pouring. 

Small  molds  are  set  on  the  foundry  floor,  but  with  larger  sizes 
it  is  generally  necessary  to  place  them  in  a  pit  (casting  pit, 
foundry  pit,  or  open  pit)  so  their  tops  will  be  readily  accessible; 
also  to  save  the  use  of  flasks.  With  ingots,  the  latter  method 
(pit  casting)  has  been  almost  entirely  abandoned,  having  been 
superseded  by  setting  the  molds  on  small  cars  or  buggies  (car 
casting,  buggy  or  bogey  casting)  so  they  may  be  removed 
expeditiously  to  the  stripper  (a  machine  for  stripping  the  ingots, 
i.e.,  lifting  off  the  molds),  and  thence  to  the  heating  furnaces  for 
rolling  or  forging.  The  plate  or  base  upon  which  an  open  bottom 
mold  stands  is  called  the  stooi.  Open  sand  castings  are  those 
made  in  molds  simply  excavated  in  sand  without  flasks.  When 
molten  metal  breaks  through  the  mold  the  latter  is  called  a 
running  mold.  An  ingot  which  is  rolled  or  forged  while  the  interior 
is  still  liquid  is  termed  a  green  ingot,  and  if  it_cracks  so  some  of  the 


8  CASTING 

interior  escapes,  a  bled  ingot.  Chilled  or  (rarely)  hardened  cast- 
ings are  usually  of  cast  iron  which  have  been  set  in  metal  molds, 
or  where  certain  portions  have  been  chilled  by  contact  with  metal 
pieces  set  the  walls  of  the  mold. 

A  casting  is  said  to  be  sharp  when  it  conforms  accurately 
to  the  mold.  Veins  are  irregular  wavy  markings  on  the  surface 
of  castings  which  occur  when  too  much  blacking,  etc.,  has  been 
used  to  coat  the  molds.  Feathers  are  small  fins  or  excrescences 
of  metal  which  have  run  between  the  joints  of  the  mold.  Scabs 
are  rough  projections  on  a  casting  caused  by  the  mold  breaking  or 
being  washed  by  the  molten  metal.  Buckles  or  swells  on  castings 
are  caused  by  the  mold  being  pushed  out  of  shape  by  the  molten 
metal.  In  an  iron  casting  a  hot  spot  is  a  place  where  segregation 
is  high;  such  spots  are  sometimes  porous  or  surrounded  by  porous 
metal.  To  prepare  a  casting  for  use,  it  is  necessary  to  clean  it, 


PIG.   12. — Ingot  split  longitudinally  showing  pipe. 

i.e.,  remove  the  gates,  fins,  scabs,  and  adhering  sand.  Smoothing 
up  the  surface  with  grinding  wheels,  etc.,  particularly  where  the 
runners  and  sinkhead  have  been  broken  off,  is  referred  to  as 
dressing  or  fettling.  The  sand  adheres  much  more  tenaciously  to 
castings  of  steel  than  to  those  of  cast  iron;  in  the  former  case  it 
may  be  necessary  to  use  a  chisel  and  sledge  or  a  pneumatic 
chipper;  in  the  latter  case  the  castings,  if  small,  are  frequently 
put  in  a  machine  resembling  a  barrel  in  which  they  are  rotated, 
usually  with  some  sharp  pointed  pieces  of  metal,  by  means  of 
which  the  sand  is  removed  and  the  surface  polished;  this  machine 
is  called  a  rumble,  rattle  barrel,  tumbler,  tumbling  barrel, 
or  shaking  barrel.  Where  castings  have  to  be  fitted  to  each 
other  or  to  some  object,  the  faces  which  are  to  come  into  contact 
are  frequently  provided  with  thin  metal  strips  cast  on,  which  can 
be  cut  until  an  accurate  fit  is  obtained;  these  are  called  chipping 
pieces  or  chipping  strips,  and  their  faces  chipping  faces. 

Steel  castings  may  be  regularly  annealed  after  removal  from 
the  molds  by  reheating  in  a  furnace  to  a  cherry  red  for  a  certain 
length  of  time  (a)  to  remove  any  cooling  strains,  and  (6)  to  give 
a  finer  grain.  Sometimes  to  avoid  cooling-strains  they  are  al- 
lowed to  cool  slowly  in  the  mold,  and  this  is  referred  to  as  flask 
annealing.  In  the  case  of  cast-iron  car  wheels  they  are  removed 
from  the  chill  molds  as  soon  as  possible  and  are  frequently  piled, 
about  six  deep,  in  a  circular  pit  provided  with  a  cover,  and  there 
allowed  to  cool  slowly  (pit  annealing) . 


CASTING  59 

Special  methods  of  casting  in  some  cases  have  for  their  object 
a  cheaper  or  more  rapid  operation,  but  in  most  cases  are  con- 
cerned with  the  production  of  sound  steel,  i.e.,  free  from  piping 
and  blowholes  or  other  interior  defects,  in  which  may  be  in- 
cluded segregation.  Below  are  given  certain  processes  which  are 
usually  based  on  one  or  more  of  the  following  principles : 

1.  Mechanical  methods : 

(a)  Applying  pressure  in  the  mold  before  complete  solidifi- 
cation: fluid  compression. 

(b)  Applying  pressure  to  the  ingot  after  removal  from  the 
mold:  Talbot's  process. 

(c)  Replenishment  (top  replenishment)  of  molten  metal  at 
the  top. 

(d)  Slow  pouring. 

(e)  Increasing  blowholes  to  reduce  pipe,  and  v ice  versa. 

2.  Thermal  methods :  Retarding  the  cooling  of  the  metal  at 
the  top  in  relation  to  that  below  (Howe  refers  to  retardation  of 
cooling  at  the  top  as  top  lag). 

(a)  Top  heating:  Applying  molten  slag,  fuel,  etc. 

(b)  Top  insulation:  A  refractory  lining  at  the  top  of  the 
mold  (dozzle);  sand,  lime,  etc.,  thrown  on  top  of  the 
casting,  or  even  contact  with  the  air.     An  ingot  is 
dozzled  (Eng.)  when  the  mold  has  a  refractory  top. 

(c)  Increasing  cooling  effect  at  the  bottom  by  inserting 
metal  pieces  (for  sand  molds)  or  increasing  the  section 
(for  metal  molds). 

(d)  The  addition  of  a  substance  such  as  thermit  to  increase 
the  temperature  at  the  top. 

(e}  Inverted  molds  (large  end  up). 

(/)  Charging  ingots  hot  in  the  soaking  pits. 

3.  Chemical  methods :  The  addition  of  aluminum,  silicon,  etc., 
to  remove  gases  or  cause  them  to  remain  in  solution  after  solidifi- 
cation. 

Piping  is  increased  by  i  (e}  if  blowholes  are  decreased;  by  3. 
Blowholes  are  increased  by  i  (e)  if  piping  is  reduced. 

Special  methods  of  pouring. — Pouring  or  teeming  is  the 
operation  of  filling  molds  with  molten  metal,  while  the  produc- 
tion of  castings  in  general  is  termed  casting.  With  cast  iron, 
the  ladle  is  practically  always  top  pouring  (see  Ladle),  the  small 
amount  of  slag  floating  on  top  of  the  metal  being  kept  back  with 
bars.  With  steel,  the  bottom  pouring  style  of  ladle  is  almost 
universally  employed  on  account  of  the  large  amount  of  slag 
which  must  be  prevented  from  entering  the  molds,  and  also  the 
necessity  for  avoiding  splashing  the  sides  of  the  molds.  Ordi- 
narily the  same  ladle  into  which  the  steel  is  run  from  the  furnace 
or  converter  is  used  for  pouring.  To  insure  better  mixing  (par- 
ticularly of  small  charges)  the  steel  is  sometimes  poured'  from  one 
ladle  into  another  (repouring  process),  and  if  this  is  done  through 
the  bottom  of  the  first  ladle,  instead  of  over  the  top,  it  will  elimi- 
nate almost  entirely  the  slag,  and  so  permit  additions  to  be  made 


60  CASTING 

in  the  second  ladle  without  any  danger  of  rephosphorization. 
In  Caspersson's  method  of  pouring,  the  steel  is  run  into  a  vessel 
with  a  number  of  perforations  in  the  bottom  (colander  funnel) 
which  divide  it  up  into  a  number  of  fine  streams  with  the  object  of 
giving  the  contained  gases  a  better  opportunity  to  escape. 
Sauveur's  overflow  method  of  pouring  was  devised  for  the  preven- 
tion of  pipes  in  ingots,  by  having  each  mold  overflow  into  the 
next,  and  thus  have  a  quantity  of  molten  steel  constantly  on  top 
of  each  ingot  until  the  ingot  had  almost  completely  solidified. 
Owing  to  early  chilling  of  the  stream,  it  was  found  applicable 
only  to  small  ingots,  and  there  were  also  difficulties  in  handling 
from  having  to  break  the  ingots  apart.  In  the  Beardmore  and 
Cherrie  process  a  shallow  mold  with  a  large  surface  is  employed 
instead  of  the  ordinary  deep  type,  with  the  idea  of  promoting 
the  escape  of  gases,  and  so  reducing  the  number  of  blowholes. 
Van  Riet  claimed  to  avoid  the  formation  of  blowholes  by  placing 
on  top  of  the  mold  a  box  with  a  small  hole  in  the  bottom  arranged 
to  prevent  the  slag  from  running  in;  it  would  not  appear  to  be  of 
much  value  unless  a  top-pouring  ladle  were  used.  To  shorten 
the  fall  of  the  steel,  and  so  prevent  the  entraining  of  air,  Billing 
employed  a  mold  with  a  piston  forming  the  bottom  and  so  ar- 
ranged that,  starting  at  the  top  of  the  mold,  it  could  be  lowered  as 
the  mold  was  filled.  In  Hainsworth's  method  the  steel  from  a 
converter  is  poured  into  a  deep  stopperless  runner  which  dis- 
charges into  the  molds,  preferably  through  an  intermediate 
stopperless  funnel  with  several  nozzles,  one  over  each  mold.  To 
prevent  splashing  the  sides  of  the  mold,  Posnikoff  suspends  in 
the  mold  a  thin  sheet-iron  tube  through  which  the  steel  is 
poured;  this  melts  as  the  steel  rises  over  it. 

Regulating  the  Rate  of  Cooling. — The  Ansaldo  process  is  on  the 
same  principle  as  an  electric  induction  furnace.  The  metal  in  the 
mold  is  heated  by  a  secondary  current  induced  by  the  primary 
current  in  a  coil  of  wire  surrounding  the  mold.  This  coil  can  be 
moved  vertically  so  that  when  the  mold  has  been  filled  it  occupies 
a  position  at  the  top  of  the  mold  to  keep  the  metal  molten  there  as 
desired.  The  De  Laval  feeding  head  (De  Laval  ring)  consists 
of  a  conical  or  funnel-shaped  crown  lined  with  refractory  material 
heated  to  at  least  a  red  heat.  This  is  placed  on  top  of  the  mold 
during  pouring,  and  afterward  helps  to  keep  the  steel  liquid  at  that 
point  so  it  will  fill  any  pipe  which  tends  to  form.  The  Gathmann 
process  consists  in  casting  ingots  in  inverted  molds,  the  bottom 
portion  having  much  thicker  walls,  the  object  sought  by  both 
these  means  being  to  decrease  the  rate  of  cooling  at  the  top  and 
increase  it  at  the  bottom  of  the  ingot.  In  the  Hadfield  process 
the  ingots  are  cast  with  the  large  end  up.  On  top  of  the  mold  is 
placed  a  cast  iron  box  lined  with  refractory  material,  the  mold 
being  filled  with  steel  to  within  a  few  inches  of  the  top  of  this  box. 
A  small  amount  of  fusible  crushed  slag  is  thrown  on,  and,  when 
this  is  melted,  charcoal  is  also  added.  A  weak  blast,  in  a  series 
of  jets,  impinges  on  the  charcoal  to  promote  its  combustion,  the 
temperature  secured  being  sufficient  to  keep  the  steel  in  the  hot 
top  fluid  and  so  fill  up  any  pipe  forming  beneath.  In  J.  Munton's 


CASTING  6 1 

method  attainment  of  the  same  object  is  sought  by  pouring, 
molten  slag  on  top  of  the  ingot  before  the  steel  has  solidified. 
J.  B.  Nau  attempts  the  same  thing  in  a  somewhat  different 
manner:  the  ingpt  mold  constitutes  the  bottom  or  hearth  of  a 
heating  furnace,  and  is  arranged  so  it  can  be  lowered;  the  bottom 
of  the  mold  is  cooled  by  a  series  of  water  pipes  so  the  cooling  of  the 
ingot  will  proceed  from  the  bottom  upward.  Riemer's  method 
is  to  use  a  gas  flame  for  heating  the  top  of  the  ingot.  Thermit 
(see  Goldschmidt  Process),  also  called  anti-piping  thermit,  has 
been  employed  to  reduce  piping,  a  can  of  the  thermit  attached  to 
an  iron  rod  being  thrust  into  the  steel  near  the  top,  after  the  mold 
has  been  filled,  so  that  the  heat  generated  by  the  reaction  will 
keep  it  molten.  A  later  development  is  to  thrust  the  can  down  as 
near  the  bottom  of  the  mold  as  possible  so  the  reaction  will  stir 
up  the  metal  and  thus  give  the  gases  a  better  chance  to  escape; 
fresh  metal  from  a  ladle  may  also  be  added  to  keep  the  mold  full. 
Group  casting  is  where  a  number  of  molds  on  one  bottom  plate 
are  bottom  poured  simultaneously  by  means  of  a  central  runner 
(git)  or  mold  (git  mold)  into  which  the  steel  is  run.  This  is 
sometimes  referred  to  as  the  hen  and  chickens  method.  In  the 
Pink  method,  the  molds  are  supported  on  a  turntable.  A  modi- 
fication of  group  casting,  usually  termed  multiple  casting,  is 
where  a  number  of  molds  are  superposed  and  fed  through  a 
common  runner.  In  Scott's  method  (intended  for  tire  ingots) 
the  molds  are  built  up  with  cast-iron  rings  and  fire-brick  slabs 
with  a  small  central  hole  interposed  to  make  several  cheeses 
(round  slabs  for  forging  into  railroad  tires)  which  are  readily 
broken  apart  after  solidifying.  The  pouring  is  done  from  the 
bottom.  Turner  combines  several  molds  in  one  larger  mold,  and 
also  piles  several  on  top  of  each  other,  separated  by  division 
bricks  provided  with  small  holes.  They  are  fed  at  the  bottom  of 
the  lowest  mold  by  a  runner.  J.  B.  D'A.  Boulton's  method  con- 
sists in  employing  ingot  molds  without  bottoms  which  are 
superposed;  they  are  filled  successively,  and  the  shrinkage 
in  each  is  compensated  by  fluid  metal  from  the  ingot  above; 
an  asbestos  washer  with  a  small  aperture  is  placed  between  the 
ingots  so  the  bottom  one  can  be  easily  removed.  The  operation 
is  intended  to  be  continuous,  the  ingots  being  sheared  off  at  the 
bottom  (the  molds  are  split  longitudinally  so  as  to  be  easily 
removed),  and  fresh  molds  set  in  position  on  top  of  those 
already  filled;  the  lowering  of  the  molds  is  performed  by 
hydraulic  mechanism.  A.  Kurzwernhart  and  C.  Bertrand  have 
suggested  a  method  with  several  modifications :  the  ingot  mold 
consists  of  two  portions,  a  lower,  divided  into  several  smaller 
molds,  and  an  upper  undivided  one.  The  sides  of  the  two  main 
portions  are  kept  separate  by  means  of  a  slab  of  fire-brick 
inserted  between  them.  By  this  means  the  portions  may  be 
easily  separated  after  the  casting  of  the  ingots.  The  upper 
portion  of  the  mold  is  comparatively  shallow,  and  is  lined 
with  refractory  material,  termed  the  gas  collector,  and  it  is 
claimed  its  use  permits  of  very  small  and  sound  ingots  being 
produced.  In  R.  Smith-Casson's  method  a  split  mold  is  em- 


62  CASTING 

ployed  with  divisions  nearly  coming  together  so  the  ingots  are 
connected  at  the  two  opposite  edges  by  small  webs  of  metal,  and 
can  later  be  separated  by  a  blow  of  a  sledge  or  else  sheared 
off;  they  are  bottom  cast.  J.  Parkes  causes  metal  to  rise  upward 
through  a  series  of  slab  molds  of  different  and  gradually  diminish- 
ing sizes  with  the  idea  of  producing  pieces  of  steel  of  nearly  the 
size  desired  for  plates,  etc.,  free  from  blowholes  by  the  pressure 
Of  the  long  column. 

Mechanical  treatment  for  producing  solid  castings. — See 
also  Fluid  Compression.  Vacuum  casting  consists  in  creating 
a  partial  vacuum  in  the  mold  after  pouring  the  steel,  to  remove 
the  dissolved  or  occluded  gases,  and  so  prevent  the  formation 
of  blowholes.  Forsyth  rapidly  hammers  the  mold  after  pour- 
ing, the  jarring  of  the  steel  interfering  with  coarse  crystalliza- 
tion. F.  Kapfl  gives  slight  vertical  jerks  to  the  mold  and  its 
contents  during  the  progress  of  solidification.  Chernoff  agitates 
the  metal  during  solidification  by  rotating  the  mold  at  varying 
speeds  with  occasional  reversals.  R.  W.  Hinsdale  has  devised 
two  methods.  In  the  first  he  uses  a  single  stationary,  bottomless, 
water  or  steam-cooled  mold.  The  ingot  is  drawn  down  by  mech- 
anism as  soon  as  its  crust  has  solidified,  till  only  its  upper  end 
remains  in  the  mold,  when  a  second  is  cast  upon  it,  uniting  with  it 
in  the  center,  and  feeding  its  pipe,  yet  readily  detached  later. 
There  must  be  little  or  no  taper  to  the  mold,  so  there  is  danger  of 
the  ingot  cracking  and  bleeding.  In  the  second  method  the  mold 
is  mounted  on  trunnions;  after  pouring,  the  top  of  the  ingot  is 
chilled,  and  the  mold  turned  upside  down  with  the  purpose  of 
having  the  pipe  entirely  enclosed  by  steel,  so  the  interior  of  the 
pipe  will  not  be  oxidized,  and  will  weld  up  on  subsequent  working. 
A  method  which  may  be  mentioned  here  consists  in  stirring  up 
the  steel  in  the  ladle  with  a  machine  known  as  Allen's  agitator. 
This  has  two  arms  fastened  to  a  revolving  shaft  which  ^can  be 
raised  or  lowered.  It  was  primarily  intended  for  mixing  the 
additions  with-  the  steel,  but  was  also  found  to  effect  a  con- 
siderable evolution  of  gas  and  so  reduce  the  number  of  blow- 
holes in  the  ingots.  An  operation  termed  poling  is  sometimes 
employed  for  nearly  the  same  purpose:  a  pole  of  green  wood 
is  thrust  into  the  steel  in  a  ladle,  and  the  gases  distilled  off  serve 
to  stir  up  the  contents,  and  also  exert  a  certain  amount  of  re- 
ducing action  on  any  oxides  present.  This  method  has  also 
been  tried  with  cast  iron  for  foundry  work  with  the  idea  that  a 
certain  amount  of  purification  will  result.  Centrifugal  casting 
consists  in  rotating  or  revolving  the  molds  after  pouring,  and  while 
the  steel  is  still  molten.  The  pressure  exerted,  which  is  much  less 
than  with  fluid  compression,  tends  to  remove  the  occluded  gases 
and  produce  sound  castings.  L.  Sebenius  pivoted  the  ingot 
molds  on  swinging  arms  which  were  rotated  at  a  rate  of  about 
125  revolutions  per  minute,  so  that  the  molds  were  caused  to  take 
a  horizontal  position.  In  Stridsberg's  modification  the  mold  was 
rotated  about  its  longitudinal  axis  instead  of  having  it  as  the 
radius.  P.  Huth's  method  was  devised  especially  for  producing 
wheels,  etc.,  with  a  hard  rim  or  face  and  a  soft  interior.  The 


CASTING  63 

mold  was  caused  to  rotate  about  its  center  as  an  axis,  and  hard 
steel  was  poured  in  first  and  thrown  to  the  circumference  of  the 
mold;  soft  steel  was  then  run  in  to  complete  the  center.  Of 
course  any  other  combination  could  be  made. 
Fluid  Compression. — Also  called  liquid  compression  or  plastic 
compression,  has  for  its  object  the  treatment  of  ingots  to  make 
them  perfectly  solid  throughout  by  the  elimination  of  blowholes 
and  pipe.  It  consists  in  applying  pressure  in  some  form  to  the 
steel  while  it  is  solidifying.  In  the  earlier  methods  gaseous 
pressure  was  applied  between  the  top  of  the  ingot  and  the  top 
of  the  mold  (closed  after  pouring).  Bessemer's  process  con- 
sisted in  the  combustion  of  gas-yielding  substances,  and  in  the 
vaporization  of  certain  liquids.  In  W.  A.  Jones'  process  steam 
under  considerable  pressure  was  introduced.  In  Krupp's  process 
liquid  carbonic  acid  gas  was  used.  The  La  Chaleassiere  process, 
like  Jones',  consisted  in  casting  under  a  steam  pressure  of  88  to 
147  pounds  to  the  square  inch.  -In  the  Galy-Cazalet  process  a 
mixture  of  charcoal  and  saltpeter  (similar  to  gunpowder  with  the 
sulphur  left  out)  was  used. 

In  the  Whitworth  process  the  steel  is  cast  in  a  cylindrical 
mold  with-  vertical  walls,  and  a  hydraulic  plunger  is  forced 
down  on  top  of  the  ingot.  Hinsdale's  process  is  somewhat 
similar  to  Whitworth's:  a  plunger  with  a  hollow  end  is  brought 
down  on  top  of  the  ingot  and  breaks  through  the  upper  crust; 
the  liquid  steel  which  enters  this  hollow  is  stated  to  be  the 
only  scrap;  it  was  employed  for  small,  high-carbon  ingots. 
In  G.  W.  Billing's  process  a  common  mold  was  used,  its  bottom 
being  replaced  by  a  piston  which  was  forced  upward  as  soon 
as  pouring  was  completed,  the  top  of  the  ingot  being  pressed 
against  a  resistance  plate  which  had  meanwhile  been  slipped 
in  (Howe).  In  Daelen's  process  the  steel  was  cast  in  a  power- 
fully clamped  iron  mold.  If  top  cast,  a  plunger  was  driven 
through  a  hole  in  the  top  of  the  mold,  its  cross-section,  being 
only  a  small  part  of  that  of  the  ingot.  If  bottom  cast,  a  plunger 
was  driven  in  horizontally  into  the  runner  which  was  larger  at 
that  point,  the  top  of  the  mold  being  closed  (Howe).  In  the 
Neuberg  process  the  steel  is  cast  in  tapered  molds,  reinforced 
by  steel  hoops  which  are  shrunk  on.  The  inside  is  hexagonal 
in  section  except  for  about  6"  at  the  top  which  is  circular  to 
admit  the  plunger  of  a  hydraulic  press  which  exerts  a  pressure 
of  400  to  700  tons  for  about  half  a  minute  to  a  minute.  In  S.  T. 
Williams'  process  the  ingot  is  cast  in  an  ordinary  tapered  mold, 
one  side  of  which  is  removable;  when  the  walls  of  the  ingot  are 
sufficiently  thick,  a  convex  liner  is  slipped  inside  the  removable 
side  of  the  mold  and  forced  against  the  ingot.  Lilienberg's 
process  is  somewhat  similar:  Ingots  are  cast  in  the  ordinary 
manner,  which,  after  removing  the  molds,  are  pressed  between 
two  wails,  one  of  which  is  movable  and  the  other  stationary. 
Illingwortn's  method  was  to  employ  a  split  mold  with  a  metallic 
filler  which  was  removed  when  the  ingot  had  partially  set  and 
pressure  was  applied.  H.  D.  Hibbard's  method  was  similar  to 
Illingworth's  except  a  refractory  filler  was  employed  and  the  ingot 


64  CASTING 

was  cast  with  the  large  end  up.  In  Harmet's  process  (also 
called  St.  Etienne  process,  compression  by  wire  drawing,  or 
draft  fluid  compression)  a  tapered  ingot  is  driven  upward  in  a 
.  tapered  mold  by  means  of  a  hydraulic  plunger,  the  wedge  action 
exerting  enormous  pressure  on  the  sides.  Talbot's  process 
consists  essentially  in  removing  the  ingot  from  the  soaking  pit 
before  the  central  portion  has  solidified,  reducing  it  partially  in  a 
blooming  mill  with  the  object  of  closing  up  any  cavities,  and  then 
restoring  it  to  the  soaking  pit  until  it  is  in  the  usual  condition 
for  rolling,  after  which  the  rolling  is  finished  in  the  regular  way. 
The  term  liquid  squeezed  has  been  applied  to  steel  treated  in  this 
manner. 

Compound  or  composite  castings  (ingots)  are  those  made  by 
combining  together  different  grades  of  steel,  sometimes  with 
wrought  iron,  so  that  certain  parts  of  the  casting  will  be  hard, 
while  others  will  be  soft  and  tough.  This  method  is  intended 
principally  for  ingots  to  be  rolled  or  forged  into  various  articles 
such  as  armor  plate,  etc.  Where  the  center  is  soft  while  the 
outside-  is  hard,  the  term  soft  centered  (mild  centered)  steel 
is  applied;  in  the  reverse  case,  hard  centered  steel.  In  the 
Wild  process  ingots  were  to  be  formed  of  wrought  iron  and 
steel  by  taking  a  piece  of  iron  of  the  desired  shape,  heating  it 
to  a  welding  heat,  placing  it  in  the  mold,  and  pouring  steel 
around  it;  there  was  trouble  from  oxidation  of  the  iron,  and 
also  the  iron  was  found  to  roll  out  faster  than  the  steel.  Von 
Nawrocki  divided  the  mold  into  two  or  more  parts  by  thin 
sheets  of  wrought  iron,  when  steel  and  iron  (soft  steel?)  were 
run  into  the  separate  compartments.  Congreaves  patent 
composite  steel,  or  compo,  intended  for  axles,  boiler  plate,  etc., 
was  produced  by  placing  in  the  mold  a  cage  of  wrought-iron 
bars  separated  by  perforated  plates,  around  which  steel  was 
poured.  Sibut's  process  is  very  similar  to  the  above.  In  the 
process  devised  by  Marel  Brothers  (for  armor  plate)  a  ribbed 
plate  of  wrought  iron  was  first  made.  This  was  heated  to  a  white 
heat,  sprinkled  with  borax,  and  in  this  condition  put  in  a  mold, 
and  molten  steel  run  around  it  or  merely  against  one  face; 
the  ingot  was  subsequently  worked  down.  Wm.  Siemens 
poured  hard  steel  upon  softer,  or  divided  up  the  ingot  mold  in 
some  way.  B.  Lauth  proposed  a^very  similar  method.  In 
the  process  devised  by  Evans  and  Spencer  for  producing  suitable 
material  for  axles  and  shafts,  a  central  core  of  wrought  iron  was 
placed  in  the  mold,  and  around  this  a  harder  grade  of  steel  was 
run,  and  the  ingot  subsequently  worked  down.  Elbridge 
Wheeler  used  two  grades  of  steel  from  two  converters;  metal 
of  one  grade  was  poured  into  a  mold  provided  with  a  core  which 
was  then  removed  and  the  other  grade  run  into  the  cavity. 
Charles  Saunderson's  process  consisted  in  making  blooms  of 
wrought  iron  containing  grooves  over  which  iron  strips  were 
welded,  and  the  holes  thus  formed  were  filled  with  steel.  In  a 
modification,  he  surrounded  a  bloom  with  a  tube,  and  filled  the 
space  with  steel.  In  either  case  the  product  was  heated  and 
worked  down. 


CASTING  BOIL— CASTING  SHOE  65 

Miscellaneous  methods.— The  Szekely  method"  consists  in 
employing  metal  molds,  one  of  the  chief  points  being  to  coat  the 
molds  with  chalk  and  paraffin.  Shaw  also  employs  metal  molds. 
Slavianoff's  electric  casting  method  appears  to  be  simply  a 
method  of  melting  steel  by  connecting  it  to  one  terminal  of  a 
strong  electric  circuit,  the  crucible  in  which  it  is  to  be  melted,  or 
the  plate  on  which  it  is  to  be  cast  being  attached  to  the  other. 
In  the  so-called  sand  core  process,  a  sand  core  is  cast  in  the  ingot 
which  is  afterward  worked  down  as  usual;  it  was  claimed  that 
the  sand  did  not  injure  the  material,  but  this,  as  well  as  any 
advantage  is  extremely  doubtful.  In  Norton's  fluid  rolling 
process,  fluid  steel  was  to  be  worked  direct  into  sheets  by  pouring 
it  through  revolving  rolls  properly  adjusted,  with  the  idea  of 
preventing  blowholes,  and  reducing  the  usual  amount  of  scale. 
Bessemer's  method  for  making  continuous  sheets  consisted  m 
running  molten  steel  between  two  water-cooled  steel  rolls, 
separated  a  suitable  distance;  the  speed  of  the  rolls  was  regulated 
according  to  the  thickness  of  the  sheet.  In  Whiteley's  process 
for  the  production  of  plates,  molten  steel  was  run  into  a  revolving 
cylinder  and  formed  a  shell  which  was  taken  out,  cut  open  by 
a  saw,  and  then  rolled  down.  Pielsticker  and  Mueller's  process 
was  devised  for  producing  bars,  rods,  and  similar  material  direct 
from  fluid  steel  by  first  passing  it  through  dies,  and  then  finishing 
the  resultant  material  in  a  rolling  mill  or  under  a  hammer. 
Mellen  rod  casting  process  employs  a  special  machine  tor  t 
continuous  production  of  rods;  molten  metal  is  poured  into  the 
molds  arranged  in  an  endless  chain. 

Malleable  or  cast-iron  castings  are  sometimes  united  ^by 
heating  in  contact  to  a  high  temperature;  this  is  termed  burning 
together.  It  is  sometimes  necessary  to  make  an  addition  to  a 
casting  to  complete  or  to  replace  a  portion  which  has  been  broken 
off.  For  this  purpose  the  casting  already  made  is  placed  in  a 
mold  of  the  proper  shape  and  molten  metal  poured  in.  The  solid 
metal  must  be  heated  up  to  a  sufficiently  high  temperature,  and 
there  are  two  methods  which  are  usually  distinguished  as  (a) 
casting  on,  where  the  solid  metal  is  heated  with  a  flame,  and  (b) 
burning  on,  where  the  molten  metal  is  first  caused  to  run  into 
and  out  of  the  mold  until  the  solid  portion  has  been  sufficiently 
heated,  when  the  outlet  hole  is  closed,  and  the  mold  allowed  to 
fill  up.  Wm.  Chalk's  method  for  uniting  a  sleeve  or  boss  of  cast 
iron,  etc.,  on  a  wrought-iron  shaft  consists  in  heating  the  shaft 
to  a  welding  temperature,  putting  it  in  a  suitable  mold,  and  pour- 
ing around  it  the  molten  metal.  Falk's  method  is  somewhat 
similar,  and  is  intended  for  uniting  the  ends  of  rails;  an  iron  mold 
is  placed  around  the  ends,  and  extremely  hot  metal  is  then 
poured  around  them  until  they  are  partially  fused  and  will  unite 
readily. 

Casting  Boil.— See  page  57- 
Casting  Box.— See  page  297. 
Casting  On. — Form  of  soldering:  see  above. 
Casting  Pit— See  page  57- 
Casting  Shoe.— The  fore-hearth  for  an  open  hearth  furnace. 


66  CASTING  STRAINS— CEMENTATION 

Casting  Strains. — See  page  56. 

Catalan  Forge;  Process. — See  page  138. 

Catalysis;  Catalyst;  Catalytic  Agent. — See  page  87. 

Catalysis  Theory. — Of  passivity:  see  page  364. 

Catch  the  Carbon  on  the  Way  Down.— See  page  315. 

Catcher. — See  page  430. 

Catcher's  Side. — See  page  41$. 

Cathode. — See  page  89. 

Cation. — See  page  89. 

Cat's  Eyes. — See  page  1 14. 

Caustic  Potash ;  Soda.— The  commercial  hydrate  or  hydroxide  of 
potassium  and  sodium  respectively. 

Cave. — Crucible  furnace:  see  page  114. 

Cavity. — Pipe  or  gas  pocket:  see  page  53. 

Celite. — See  page  396. 

Cell. — See  page  121. 

Cell  Wall.— See  pages  121  and- 126. 

Cellular  Deformation. — See  page  126. 

Cellular  Theory. — Of  steel:  That  when  solid  it  consists  of  a  net- 
work of  grains  or  crystals. 

Celsius  Scale. — Of  temperature  degrees:  see  page  204. 

Cement. — (i)  In  cementation:  see  pages  67  and  70;  (2)  binding 
the  grains  of  metals:  see  page  281.  . 

Cement  Bars. — See  page  71. 

Cement  Carbon. — See  page  272. 

Cement  Steel. — See  page  71. 

Cement  Theory. — See  page  281. 

Cementation. — (i)  In  the  metallurgy  of  iron  and  steel  the  carburi- 
zation,  or  impregnation  with  carbon,  at  a  temperature  below  the 
melting  point  of  the  metal.  The  iron  must  be  in  intimate  contact 
with  the  carbonaceous  matter,  and  air  must  be  excluded.  While 
the  general  principles  are  the  same,  there  are  three  modifications 
which  are  readily  classified  in  accordance  with  the  depth  and  the 
nature  of  the  carburization :  (a)  bars  carburized  throughout 
or  nearly  so  to  a  varying  degree — referred  to  specifically  as  the 
cementation  process — used  in  the  crucible  process  and  also  in  the 
manufacture  of  cutting  tools;  (6)  armor  plate  (q.v.),  deeply 
impregnated  but  on  one  side  only;  (c)  where  the  depth  of  pene- 
tration is  very  slight,  usually  called  case  hardening,  for  objects 
or  parts  of  objects  which  must  be  superficially  hard  to  resist 
wear.  (2)  Metallic  cementation  (see  also  Protection,  page  370), 
a  term  used  to  denote  impregnation  with  a  metal  or  alloy  in 
much  the  same  manner  as  with  carbon,  resulting  in  a  metallic 
coating  for  the  purpose  of  resisting  corrosion.  Siliciuration 
indicates  impregnation  with  silicon,  as  when  platinum  is  heated 
in  contact  with  silicious  material  and  hydrogen.  (3)  Rarely 
used  in  the  sense  of  treating  solid  cast  iron  with  oxides  to  effect 
its  decarburization  (see  Malleable  Castings,  page  257).  (4) 
Rarely  the  reduction,  without  fusion,  of  iron  ore  by  means  of 
carbonaceous  material  (see  Direct  Processes,  page  134). 

For  the  general  process  of  cementation  the  terms  carbonization, 
carbonizing  process,   and  carburizing  process  are  also  used. 


CEMENTATION  67 

Cementation  which  is  wholly  or  almost  complete  is  sometimes 
called  total  cementation  to  distinguish  it  from  case  hardening 
which  is  also  known  as  partial  cementation,  surface  cementation, 
superficial  cementation,  case  carbonizing,  rarely  burning  in, 
and  sometimes  (especially  in  the  case  of  gears  and  pinions) 
armored  or  armorized.  The  term  supercarburized  has  been 
applied  to  armor  made  by  the  Harvey  process.  Where  the  cemen- 
tation is  partial,  the  (outer)  portion  affected,  the  cemented 
zone,  is  called  the  case,  and  the  inner  unaffected  portion  the 
core,  heart  or  nucleus.  These  two  last  terms  are  more  usually 
restricted  to  blister  bars  not  completely  cemented,  otherwise  they 
would  be  distinguished  as  core  cemented. 

The  carbonaceous  material  used  is  the  cement.  Depending 
upon  its  state  it  may  be  solid,  liquid,  gaseous,  or,  if  a  com- 
bination of  two  or  all,  mixed.  It  may  be  further  classed,  ac- 
cording to  its  rate  of  action,  into  mild,  slow  or  gradual; 
quick  or  rapid;  and  violent  or  sudden.  In  general  the  velocity 
of  cementation  depends  upon  the  rate  of  penetration  of  the  car- 
bon. This  in  turn  is  differently  affected  by  different  elements 
which  may  be  present  in  the  metal.  On  the  basis  of  certain 
experiments  Guillet  considers  it  proved  that  the  substances 
which  retard  cementation  are  those  which  are  found  in  solution 
in  the  iron  (nickel,  titanium,  silicon,  and  aluminum) ;  and  that  the 
substances  which  accelerate  cementation  are  those  which  seem 
to  exist  in  the  state  of  double  carbides,  replacing  a  part  of  the 
iron  of  the  cementite  (manganese,  chromiam,  tungsten,  and 
molybdenum — Giolitti).  In  determining  the  rate  of  penetration 
of  carbon,  cementation  curves  may  be  employed,  which  are 
plotted  with  one  of  the  coordinates  as  the  depth  (measured  in 
mm.  or  in.)  and  the  other  as  time  (hours). 

The  temperatures  ordinarily  employed  are  850°  to  1100°  C. 
(1560°  to  2010°  F.)  and  the  rate  of  cementation  increases  with 
increase  of  temperature.  However,  with  carbon  monoxide  and 
carbonaceous  matter  the  amount  of  carbon  deposited  will  be 
greater  at  a  lower  temperature,  say  around  or  below  700°  C. 
(1290°  F.).  In  this  latter  case  the  bulk  of  the  carbon  may  be 
deposited  in  the  free  state,  that  is,  without  combining  with  or 
dissolving  in  the  iron,  by  the  same  reaction  as  occurs  in  the  blast 
furnace,  thus: 

2 CO  =  CO2  -f-  C  (deposited  in  the  iron); 
CO2  +  C  =  CO  (further  reaction  with  the  cement). 

The  equilibrium  of  the  system  CO  :  CO2 :  C  according  to  these 
reactions,  that  is,  the  carbon  concentration,  is  proportional  to  the 
concentration  of  carbon  dioxide,  and  varies  inversely  as  the 
temperature.  According  to  Boudouard  while  it  is  only  0.7% 
at  1100°  C.  (2010°  F.)  it  increases  to  42%  at  700°  C.  (1290°  F. — 
Giolitti).  These  reactions  also  take  place  in  regular  cementation. 
If,  owing  to  the  loss  of  CO2  the  efficacy  of  the  cement  is  impaired 
(exhaustion)  it  may  be  restored  by  a  short  exposure  to  the  air  or 
by  the  introduction  of  a  limited  supply  of  oxygen  while  still  hot 
(regeneration). 


68 .  CEMENTATION 

In  certain  cases  four  different  zones  may  be  observed  under  the 
microscope:  (a)  the  central  portion  of  untouched  metal  (hypo- 
eutectoid  steel),  (6)  where  the  carbon  gradually  increases  to  the 
eutectoid  content  (also  hypo-eutectoid),  (c)  eutectoid  steel,  and 
(d)  a  hyper-eutectoid  region;  there  might  also  be  included  (e) 
the  case  where,  owing  to  subsequent  oxidizing  influences,  the 
outer  portion  has  been  more  t>r  less  decarburized.  It  is  desirable 
to  avoid  any  sharp  changes  in  structure  as  these  prevent  the 
proper  continuity  and  gradation  of  the  physical  properties. 
Where  the  outer  layer  is  high  in  carbon,  say  i  to  1.5%,  it 
usually  presents  a  coarsely  crystalline  appearance  (pig  face) 
which  is  objectionable  owing  to  its  lack  of  coordination  with  the 
interior,  causing  it  to  flake  off  (exfoliation  or  splitting).  The 
separation  or  segregation  of  cementite  so  that  it  exists  in  the  free 
state  is  sometimes  called  liquation.  According  to  Giolitti,  the 
elimination  of  a  first  series  of  discontinuities — those  due  to  liqua- 
tion of  cementite — can  be  obtained  by  avoiding  the  formation  of 
a  hyper-eutectoid  layer  containing  free  cementite.  This  can  be 
done  by  the  use  of  carbon  monoxide  acting  as  an  equalizer  with 
other  cements.  Further,  to  avoid  or  reduce  in  the  cemented  and 
hardened  zones,  sudden  variations  in  the  concentration  of  carbon, 
to  which  are  due  the  phenomenon  of  exfoliation:  (i)  avoid  effect- 
ing the  cementation  at  too  low  a  temperature,  and  in  every  case 
cement  above  Ar3;  (2)  avoid  slow  cooling  after  cementation  and 
before  quenching  (to  prevent  separation  of  cementite  and  ferrite 
and  so  cause  greater  discontinuity).  Cyanides  are  not  necessary 
under  the  conditions  for  ordinary  cementation,  as  the  trans- 
portation of  carbon  to  the  metal  is  effected,  at  least  for  the 
most  part,  by  carbon  monoxide  (Giolitti). 

Of  the  solid  cements  wood  charcoal  has  been,  and  still  is, 
the  most  widely  used  particularly  for  total  cementation.  For  this 
purpose  the  temperature  is  usually  kept  at  about  the  melting 
point  of  copper,  say  1085°  C.  (1985°  F.),  and  old  and  new  char- 
coal is  employed;  if  the  charcoal  is  all  new,  a  lower  temperature 
is  necessary  to  prevent  local  o/ercarburization,  and  the  time  ex- 
tended correspondingly  to  get  the  required  depth.  Hard  wood 
charcoal  is  more  effective  than  soft  but  more  costly.  Caron's 
process,  still  used,  was  to  mix  about  40  parts  of  barium  carbonate 
with  60  parts  of  wood  charcoal  (Caron's  cement  or  hardenite). 
This  produces  a  very  active  cement  due  to  the  contained  COz; 
when  its  action  becomes  reduced  it  is  easily  restored  or  regener- 
ated by  exposing  to  the  air  while  still  hot.  Bone  dust  or  bone 
ash  is  a  solid  cement  which  evolves  a  certain  amount  of  hydro- 
carbons; after  repeated  use  it  is  termed  spent  bone.  Charred 
leather,  horns  or  hoofs,  etc.,  are  all  used,  principally  in  mixtures. 
Coke  saturated  with  a  heavy  oil  is  sometimes  employed.  For 
the  purpose  of  increasing  the  effect  by  the  action  of  cyanides, 
Eaton's  process  consisted  in  mixing  ferrocyanide  of  potash  with 
wood  charcoal.  In  Bates'  process  the  mixture  consisted  of 
carbon,  cryolite,  spent  lime,  rosin,  and  soda,  with  the  later 
addition  of  oxide  of  nickel  which  he  claimed  was  reduced  and 
formed  an  alloy  with  the  iron.  There  are  various  mixtures, 


CEMENTATION  69 

some  sold  under  trade  names,  which  are  usually  more  rather  than 
less  complicated  and  not  always  better  than  some  of  the  standard 
substances. 

Carburizing  varnishes  are  mixtures  which  can  be  painted  on 
special  parts,  and  in  addition  to  being  capable  of  imparting 
carbon  must  also  be  adherent  without  cracking  or  melting  off. 

The  use  of  liquid  or  fusible  cements  for  cementation  by 
immersion  has  been  practised  for  some  time,  usually  where  only 
a  very  thin  case  is  desired,  hence  sometimes  called  skin  harden- 
ing. Leaving  aside  the  use  of  cast  iron  which  has  been  proposed 
several  times  but  at  present  is  not  applied,  the  only  liquid  cements 
consist  of  pure  salts  or  saline  mixtures  (hence  chemical  harden- 
ing) ;  most  commonly  simple  or  complex  salts  of  prussic  (hydro- 
cyanic) acid,  either  alkali  or  alkaline  earth  cyanides,  ferro- 
cyanides  and  ferricyanides.  The  substance  most  frequently 
and  almost  exclusively  used  as  a  liquid  cement  for  cementation 
by  immersion  is  potassium  cyanide  (potash  hardening).  In 
general  the  pieces  are  immersed  in  the  already  fused  bath,  kept 
between  850°  and  900°  C.  (1560°  and  1650°  F.),  and  left  in  3 
to  15  minutes,  according  to  the  depth  of  cementation  desired. 
If  the  piece  is  of  medium  size,  say  about  i  to  6  pounds.,  and  not  too 
irregular  in  form,  the  rule  can  be  followed  to  immerse  cold,  and 
remove  when  the  temperature  has  exceeded  850  to  880°  C. 
(1560°  to  1615°  F.).  Zones  of  uniform  thickness  are  obtained 
from  0.03  to  o.io  mm.  (0.0012"  to  0.004"),  according  to  the 
temperature  and  the  time.  The  content  of  carbon  near  the 
surface  reaches  0.9%  C  or  higher,  sufficient  to  render  it,  after 
quenching,  inattackable  by  a  file.  It  is  not  advisable,  by  this 
process,  to  try  to  obtain  deeper  than  0.15  to  0.20  mm.  (0.006"  to 
0.008")  by  prolonging  the  operation  or  using  a  higher  tempera- 
ture, since  then  zones  are  obtained  in  which  excessive  percentages 
of  carbon  and  sudden  variations  give  rise,  after  quenching,  to 
intense  brittleness  and  exfoliation  (GioKtti). 

Salts  derived  from  the  radical  CN  exercise  a  specific  carburizing 
action  which  has  not  yet  been  studied  with  precision.  At  700° 
C.  (i29o°F.)  nitrogenous  cements  furnish  a  thin  cemented  zone 
with  less  than  0.55%  carbon  but  very  rich  in  nitrogen,  the  per- 
centage of  which  may  exceed  0.5%.  In  these  cemented  zones 
J.  Kirner  observed  a  special  constituent  which  he  designated 
by  the  name  flavite,  the  proportion  of  which  increased  with  in- 
crease in  the  precentage  of  nitrogen. 

A  patented  method  termed  infusion  method  of  hardening  was 
similar  to  the  above,  claims  being  made  that  owing  to  the  special 
ingredients  used  the  action  proceeded  to  a  greater  depth  and  that 
the  change  from  the  treated  to  the  untreated  parts  was  very 
gradual. 

Partially  fusible  cements  consist  of  a  mixture  of  an  infusible 
base  with  a  fusible  constituent  and  have  been  proposed  for  use 
in  a  similar  manner. 

The  gaseous  cements  may  consist  of  various  hydrocarbons 
or  carbon  monoxide,  the  advantage  being  the  uniformity  secured 
particularly  where  the  pieces  treated  are  of  complicated  shape. 


70     CEMENTATION  CARBON— CEMENTATION  PROCESS 

Carbon  monoxide  as  the  base  in  mixed  cements  acts  as  an  equali- 
zer in  securing  uniformity  and  avoiding  sharp  changes  in  content. 
The  gas  employed  may  be  diluted  by  an  inert  gas  when  it  is 
desired  to  restrain  its  action.  Carbon  monoxide,  for  example,  is 
said  to  be  isolated  when  it  is  caused  to  act  alone. 

Electrical  processes  for  cementing  (termed  by  Sang  electro- 
cementizing),  as  in  the  manufacture  of  steel,  consist  principally 
in  the  use  of  the  current  for  heating  purposes.  There  are  also 
methods  proposed  (and  patented)  from  time  to  time  by  which  it 
is  claimed  the  current  is  employed  directly  for  securing  better 
results,  the  current  acting  as  a  carrying  agent. 

An  anti-cement  is  a  coating  which  prevents  or  impedes  cemen- 
tation and  is  employed  for  the  protection  of  a  certain  part  which 
is  not  to  be  cemented;  for  example,  in  the  DeDion-Bouton 
process  copper  is  deposited  from  a  solution  of  copper  sulphate. 
The  theory  of  cementation  is  based  on  the  observed  fact  that 
certain  elements  (in  this  particular  case,  carbon)  have  the  power 
of  diffusing  through  iron.  Arnold  and  McWilliam  have  divided 
the  elements  most  commonly  found  in  steel  into  those  which  are 
migratory  and  those  which  are  fixed.  Leplay's  hypothesis  was 
that  carbon  monoxide  was  formed  by  a  reaction  of  carbonaceous 
matter  with  air  and  that  this  alone  acted  as  the  carrier  of, 
and  deposited,  carbon.  Laurent's  hypothesis  was  that  the 
cementing  action  was  due  to  a  vapor  of  carbon  and  not  to  solid 
carbon.  It  has  been  proved,  however,  that  solid  carbon,  as  such, 
has  the  power  of  diffusing  into  iron;  the  usual  action  is  due  to 
both  gases  and  to  solid  carbon. 

Cementation  Carbon.— See  page  272. 

Cementation  Curve. — See  page  67. 

Cementation  Furnace. — See  below. 

Cementation  by  Immersion. — See  page  69. 

Cementation  Process.— Also  called  converting  process.  This 
process,  in  its  special  sense,  consists  in  impregnating  bars  of 
wrought  iron  or  soft  steel  with  carbon,  at  a  temperature  below  its 
melting  point,  and  is  used  (chiefly  in  England)  for  the  production 
of  high  carbon  bars  to  be  employed  in  the  manufacture  of  crucible 
steel  or  shear  steel.  The  bars  are  usually  of  pure  Swedish  iron 
made  by  the  Walloon  process  (see  page  79),  *%"  to  3"  wide,  %" 
to  %''  thick,  and  about  12  feet  long,  8  to  13  tons  constituting  a 
charge  (Harbord  and  Hall).  They  are  packed  in  layers,  sepa- 
rated by  charcoal  (sometimes  called  cement)  in  fire-brick  cham- 
bers (converting  pots)  heated  externally  by  flues,  and  ^  forming 
part  of  the  cementing  furnace.  The  top  of  the  pot  is  closed 
with  an  arch  of  wheel  swarf,  which  later  frits  and  forms  an.  air- 
tight cover.  The  furnace  attains  its  full  temperature  in  about 
3  to  4  days,  at  which  it  is  maintained  about  7  to  8  days  for  mild 
heats,  about  9^2  days  for  medium  heats,  and  about  n  days  for 
high  carbon  heats;  the  cooling  down  requires  about  4  to  6  days. 
To  test  the  progress  of  the  operation,  trial  bars  (test-  bars,  tap 
bars,  spies,  or  regulator  test  pieces)  are  drawn  at  intervals 
through  a  special,  small  aperture,  provided  for  the  purpose,  and 
examined.  If  wrought  iron  has  been  employed,  the  finished  bars 


CEMENTATION  PROCESS  7 1 

will  be  found  covered  with  blisters  (also  rarely  called  beads  and 
bubbles)  formed  by  the  reaction  between  the  contained  slag^and 
the  carbon,  from  which  comes  the  name  blister  bar  or  blister 
steel;  at  one 'time  this  was  sometimes  termed  German  steel. 
This  phenomenon  is  absent  when  steel  bars  are  treated;  both 
products  are  known  as- converted  bars,  cement  (cemented)  bars  or 
cement  steel,  at  one  time  also  called  artificial  steel  because  not 
made  direct  from  the  ore. 

Bars  desired  of  very  high  carbon  may  be  retreated,  and  are 
known  as  doubly  converted  bars  or  glazed  bars.  Since  the 
carbon  penetrates  from  the  outside  inward,  the  percentage  will 
decrease  progressively  to  the  center.  In  very  mild  bars  there  is 
an  unaltered  core  of  mild  steel  called  sap,  and  very  hard  bars  are 
easily  distinguished  by  being  what  is  known  as  flaked,  as  on 
fracture  they  present  bright  cleavage  planes.  Two  examples  of 
this  are.  (a)  bar  W  thick,  outside,  0.98%,  center,  0.10%, 
average,  0.45%;  (6)  bar  W  thick,  outside,  1.50%,  center, 
1.15%,  average,  1.33%.  In  Sheffield  the  six  grades  of  cement 
steel  have  the  following  names: 

i.  Spring  heat carbon  about  0.50% 


2.  Country  heat. 

3.  Single -shear  heat. . . 

4.  Double-shear  heat. . 

5.  Steel-through  heat. . 

6.  Melting  heat 


0.63% 


0.75% 
1.00% 
1.25% 
1.50% 


The  sap  or  soft  center  of  No.  i  has  a  dull  appearance  (killed) 
and  does  not  stare  or  look  raw,  i.e.,  have  a  bright  fracture.  It  is 
important  to  have  the  transition  from  one  grade  to  the  other  as 
gradual  as  possible:  when  the  line  of  demarkation  is  too  abrupt, 
the  process  has  been  carried  out  too  rapidly,  and  the  bars  are  said 
to  be  flushed.  If,  owing  to  a  leak  in  the  pot,  air  has  entered,  the 
outside  of  the  bars  will  be  somewhat  oxidized,  and  are  called 
aired  bars.  If  the  temperature  has  been  a  little  too  high,  so  the 
outside  has  fused  slightly,  they  are  called  glazed  bars.  Blister 
bars  rolled  or  hammered  down  at  a  yellow  heat  are  known  as 
plated  bars  or  bar  steel.  The  following  are  various  methods 
suggested  or  tried  from  time  to  time: 

In  Bink's  process  compounds  of  cyanogen  were  specified,  and 
currents  of  nitrogen,  carbonic  oxide,  and  ammonia,  or  ammonia 
alone,  were  to  be  passed  through  decarburized  molten  iron. 

In  Bpullet's  process  iron  was  to  be  cemented  with  a  substance 
consisting  of  sugar,  horn  dust  or  shavings,  animal  fat  or  blood, 
and  wood  charcoal  dried  and  pulverized. 

In  Brooman's  process  iron  was  to  be  melted  in  pots  with 
compounds  of  cyanogen;  such  compounds  might  consist  of 
charcoal,  salt,  brick  dust  or  oxide  of  manganese,  sal  ammoniac, 
and  ferrocyanide  of  potash. 

Henry  Brown's  process  consisted  in  cementing  iron  in  a 
granulated  condition  in  close  pots  with  carbon:  iron  which  was 
being  puddled  was  taken  out  of  the  furnace  as  soon  as  it  became 
granulated,  and  before  it  was  pasty;  it  was  then  broken  up  until 


Ground 

Redbrick 

Firebrick 

•Stone 

Rubble 

Concrete 


Ground 


PIG.  13. — Transverse  section  of  cementation  converting  furnace 
— A,  converting  pots;  B,  firegrate;  C,  flues  for  distributing  heat; 
D,  short^'chimneys  communicating  with  stack;  E,  conical  hood 
or  stack;  F,  manhole  for  introducing  or  withdrawing  charge;  G, 
holes  for  removal  of  trial  bars;  H,  charging  holes.  (Harbord  and 
Hall,  "Metallurgy  of  Steel".) 


CEMENTED  ARMOR  PLATE— CHAMOTTE  73 

it  would  pass  through  a  2o-mesh  screen,  after  which  it  was  put  in 
long  pots  with  wood  and  cemented  as  usual. 

James  Boydell's  process  was  to  cement  the  product  obtained 
by  puddling  wrought  iron  melted  in  a  cupola. 

In  Holland's  process  silk  waste  of  every  kind  was  to  be  terrified, 
i.e.,  dried  at  a  high  temperature  without  being  carbonized,  and 
then  ground  to  a  fine  powder,  and  used  for  cementing. 

Kimball's  process  consisted  in  cementing  bars  with  a  special 
mixture  prepared  from  sal  ammoniac,  borax,  alum,  salt,  vinegar, 
urine,  soot,  burnt  leather,  and  horsehoofs. 

Kraff  and  Sauve's  process  consists  in  employing  charcoal, 
etc.,  previously  heated  to  about  50°  C.  (122°  F.)  and  dipped 
in  some  liquid  hydrocarbon. 

Charles  Macintosh  heated  wrought  iron  to  a  white  heat  in 
closed  pots,  and  then  introduced  carbureted  hydrogen  or  carbo- 
naceous gases  through  suitable  openings.  • 

A.  V.  Newton's  process  consisted  in  melting  pig  iron  in  a 
special  furnace,  and  blowing  on  it  jets  of  hydrocarbon  gases 
and  atmospheric  air. 

Moses  Poole  specified  the  use  of  prussiates  and  ferrocyanides. 
G.  C.  Thomas  claimed  the  decided  novelty  of  a  cementing 
(?)  mixture  consisting  of  salt,  ferrocyanide  of  potash,  bichro- 
mate of  potash,  and  animal  charcoal. 

In  Arthur  Wall's  process  iron  was  to  be  cemented  by  em- 
bedding bars,  in  an  ordinary  cementing  furnace,  in  a  mixture 
of  charcoal  and  chalk  and  zinc  filings ;  electric  currents  were 
to  be  passed  through  the  bars  for  a  certain  period. 

J.  J.  W.  Watson  claimed  the  use  of  electricity  for  carburizing 
iron;  he  also  employed  sulphate  of  manganese  with  carbona- 
ceous matter  and  lime,  either  with  or  without  the  application  of 
an  electric  current. 

Cemented  Armor  Plate. — See  page  8. 

Cemented  Bars;  Steel. — See  page  71. 

Cemented  Zone. — See  page  67. 

Cementing  Furnace. — See  page  70. 

Cementing  Fusion  Process. — See  page  113. 

Cementite. — See  page  272. 

Cementite  Carbide. — See  page  273. 

Cementite  Point. — See  page  273. 

Cementitic  Steels. — See  page  445. 

Cementito-Austenitic  Steel. — See  page  276. 

Centigrade  Scale. — Of  temperature  degrees:  see  page  204. 

Centrifugal  Casting. — See  page  62. 

Centrifugal  Extrusion. — See  page  121. 

Chafery  (obs.). — A  sort  of  blacksmith's  forge. 

Chalcopyrite.— See  page  245. 

Chalk  Method.— See  page  65. 

Chalut  and  Clouet  Process. — See  page  113. 

Chalybeate. — Containing  iron,  usually  applied  to  water. 

Chalybite. — See  page  244. 

Chambered  Core. — See  page  299. 

Chamotte. — Powder  of  old  clay  crucibles:  see  page  396. 


74  CHAMPIN  PROCESS— CHARCOAL  HEARTH 

Champin  Pneumatic  Process. — See  page  21. 

Champlain  Forge. — See  page  137. 

Channeling.— See  page  35. 

Chapelet  Furnace.— See  page  154. 

Chaplet;  Chaplet  Block;  Nail.— See  page  299. 

Chappuis  Gas  Pyrometer. — See  page  207. 

Char. — (i)  To  carbonize;  (2)  coke  or  charcoal  (Eng.). 

Charcoal. — The  carbonaceous  residue  resulting  from  the  dry 
distillation  of  wood,  amounting  to  about  26%.  Owing  to 
its  ease  of  preparation  and  its  comparative  freedom  from  sulphur 
and  ash,  it  has  long  been  used  in  certain  metallurgical  processes. 
Ledebur  gives  the  approximate  composition  of  good  air-dried 
charcoal  as: 

Volatile  matter 4% 

Fixed  carbon 84 

Ash 2 

Sulphur under    0.05 

Phosphorus 0.05 

Moisture . 10 

Red  Charcoal  is  the  name  given  to  the  product  obtained  by 
charring  wood  at  a  low  temperature  and  which  is  of  inter- 
mediate composition  between  wood  and  charcoal. 

The  wood  was  formerly  charred  exclusively  in  piles  (some- 
times called  meilers)  covered  over  with  earth  or  turf,  small 
openings  being  provided  for  the  entrance  of  the  air  and  for 
the  escape  of  the  gases.  The  most  usual  method  is  to  employ 
a  charcoal  kiln,  which  is  a  stall  consisting  of  two  side  walls 
and  a  back  wail,  the  front  and  top  being  covered  with  earth 
and  turf  as  in  the  case  of  the  pile.  It  is  now  frequently  pre- 
pared in  charcoal  ovens  or  charcoal  retorts,  similar  in  prin- 
ciple to  those  used  in  the  manufacture  of  coke;  in  the  former 
case,  combustion  of  the  gases  tukes  place  inside  the  chamber, 
while  in  the  latter,  the  chamber  is  externally  heated  by  flues 
or  a  fire. 

Charcoal  Bars. — (i)  Wrought  iron  rods  or  flats;  (2)  wrought  iron 
bars  made  by  some  charcoal  hearth  process,  or  from  charcoal  pig, 
to  be  rolled  into  sheets:  see  page  75. 

Charcoal  Blacking. — See  page  298. 

Charcoal  Finery. — See  page  383. 

Charcoal  Furnace. — See  pages  39  and  181. 

Charcoal  Hearth;  Charcoal  Hearth  Cast  Iron.— See  page  383. 

Charcoal  Hearth  Processes. — Rarely  called  forge  process ;  bustling 
and  buzzing  are  very  obsolete  terms  (Percy).  These  processes 
are  designed  for  the  production  of  wrought  iron  (charcoal  iron)," 
usually  by  refining  cast  iron,  occasionally  by  melting  scrap  before 
a  tuyere  with  charcoal  for  fuel,  the  product  being  obtained  in  a 
pasty  condition,  and  containing  a  certain  amount  of  slag,  but 
less  than  puddled  iron.  Only  the  latter  method  is  at  present 
employed  in  this  country. 

In  general  the  furnaces  or  hearths  are  (Howe)  like  the  Catalan 
and  bloomary  hearths  (see  Direct  Processes),  for  reducing  iron 


CHARCOAL  HEARTH  PROCESSES  75 

from  the  ore,  low,  rectangular  chambers,  sometimes  roofed,  and 
with  one  or  more  tuyeres.  The  chief  difference  is  that  in  refining 
cast  iron  much  more  strongly  oxidizing  conditions  are  brought 
about,  chiefly  (i)  by  melting  the  metal  down  in  drops  before 
the  tuyere,  repeatedly,  if  need  be,  so  that  it  passes  in  a  state  of 
minute  subdivision  and  with  great  surface  exposure  through  a 
part  of  the  hearth  where  the  atmospheric  oxygen  is  in  excess;  and 
(2)  by  the  action  of  the  basic  ferruginous  slag  with  which  the 
metal  is  mixed  during  the  earlier  stages,  and  with  which  it  is 
covered  during  the  later  stages,  to  ward  off  the  strongly  carburiz- 
ing  tendency  of  the  charcoal.  Only  a  good  quality  of  pig  iron 
(nearly  always  charcoal  pig)  is  used,  as  the  process  is  expensive, 
and  is  employed  only  for  a  high  grade  of  wrought  iron.  The  pig 
iron  is  often  given  a  preliminary  refining  to  eliminate  most  of  the 
silicon. 

The. hearths  are  usually  built  of  unlined  cast-iron  plates,  at 
least  in  part  water -cooied.  Brick-work  is  avoided  as  the  silica 
would  enter  the  slag. 

The  processes  may  be  classified  (Howe)  according  to  the 
number  of  times  the  metal  is  melted  down  before  the  tuyere, 
(i)  into  single  melting,  double  melting,  and  triple  melting  (or 
German  or  breaking  up) ;  (2)  into  Walloon  and  non-Walloon. 

The  hearth  may  be  covered  or  uncovered;  if  the  latter  it  is 
called  an  open  fire  or  open  hearth;  if  the  former,  a  closed  hearth 
The  bloom,  after  rolling,  is  called  finer's  bar  (corresponding  to 
muck  bar  in  puddling),  and  after  piling  and  rerolling,  finished 
charcoal  bar.  German  steel  is  an  obsolete  name  for  the  product 
obtained  by  melting  white  or  refined  pig  in  a  charcoal  hearth;  it 
may  also  be  made  of  poorer  quality  in  a  very  hot  puddling 
furnace 

Product. — "From  given  cast  iron  the  charcoal  hearth  process 
yields  better  wrought  iron  then  puddling,  perhaps  in  part  be- 
cause the  charcoal  lacks  the  sulphur  which  the  mineral  fuel 
of  the  puddling  furnace  contains,  and  of  which  a  little  may 
enter  the  metal,  but  chiefly  for  the  following  reason.  In  both 
processes  we  can  decarburize  the  pasty  metal  throughout  its 
mass  only  by  stirring  it  vigorously,  exposing  fresh  surfaces  to  the 
action  of  the  atmosphere  and  of  the  strongly  decarbunzing  basic 
slag,  and  this  stirring  intentionally  mixes  slag  with  metal  to 
effect  decarburizing.  We  thus  get  a  ball  of  stiff  pasty  wrought 
iron  mixed  with  much  slag.  In  some  of  the  charcoal  hearth 
processes  we  get  rid  of  most  of  this  slag  by  remelting  this  ball; 
holding  it  aloft  we  allow  its  metal  to  fall  drop  by  drop,  and  collect 
it  in  a  new  ball,  which  we  carefully  avoid  touching,  and  which  is 
thus  relatively  free  from  slag.  In  the  puddling  process  we  cannot 
do  this,  and  must  content  ourselves  with  squeezing  out  as  much 
of  the  slag  as  we  can  in  hammering  or  rolling.  Charcoal  iron, 
then,  is  in  a  manner  intermediate  between  common  wrought  iron 
and  ingot  iron  (fluid-cast  steel,  see  Classification)  in  that  it  is 
remelted  and  cast  while  molten  into  a  malleable  mass;  but  in- 
stead of  being  cast  into  a  slagless  mold  as  in  true  ingot-metal- 
making  processes,  it  is  poured  upon  a  bath  of  slag  of  which  a  very 


76  CHARCOAL  HEARTH  PROCESSES 

little  inevitably  becomes  mixed  with  the  metal.  Charcoal  iron 
is  raised  but  slightly  above  its  melting  point  and  for  a  few  minutes 
only;  is  cast  drop  by  drop  through  an  atmosphere  rich  in  car- 
bonic oxide  and  carbonic  acid  into  a  white-hot  bath  of  slag, 
falling  in  all  but  a  few  inches;  ingot  iron  is  held  for  a  very  con- 
siderable length  of  time  far  above  its  melting  point,  is  cast  in  a 
thick  stream,  through  a  cold  atmosphere  of  oxygen  and  nitrogen, 
usually  into  a  cold  cast-iron  mold,  often  falling  several  feet.  In 
the  charcoal  hearth,  drop  of  metal  follows  drop  in  such  a  way  that 
neither  pipe  nor  blowhole  nor  microscopic  cavity  seems  to  form; 
ingot  metal  is  so  cast  that  pipes  or  blowholes  or  microscopic 
cavities  or  all  three  arise.  Charcoal  hearth  iron  is  purposely 
kept  as  free  as  possible  from  slag,  ingot  metal  is  purposely  kept 
practically  absolutely  free  from  slag"  (Howe). 

In  the  Bohemian  process,  mottled  or  even  gray  pig  is  used, 
and  the  blooms  are  reheated  in  the  same  hearth.  Charcoal  is 
first  charged,  and  on  top  of  this  some  slag  and  the  pig  which 
is  melted  down  slowly,  the  iron  cake  which  is  formed  being 
frequently  raised  up.  The  cinder  is  tapped  at  intervals.  Finally 
the  bloom  is  welded  to  the  end  of  a  rod  and  taken  to  the  hammer; 
any  particles  of  iron  that  remain  in  the  hearth  are  retreated. 

Corinthian  process:  The  pig  used  is  white,  and  is  cast  in 
thin  disks  about  3  to  6  feet  in  diameter  and  Y±'  thick,  which  are 
given  a  preliminary  heating  or  roasting  for  about  30  hours, 
which  removes  some  of  the  carbon  as  well  as  the  silicon.  The 
disks  are  broken  up  and  piled  on  charcoal  in  the  hearth,  which 
is  of  about  the  usual  type.  The  metal  is  gradually  melted 
down,  care  being  taken  that  no  pieces  of  unmelted  metal  drop 
into  the  melted  portion.  The  bloom  is  divided  into  two  pieces, 
and  each  of  these  into  six,  which  are  reheated  in  the  same  hearth. 
A  charge  takes  about  2^4  hours. 

The  Corinthian  raw  steel  process  is  very  similar  to  the  pre- 
ceding, except  that  the  removal  of  the  carbon  is  not  carried 
so  far.  Mottled,  rarely  gray,  pig,  or  the  round  disks  described 
above,  are  used.  The  bottom  is  made  of  charcoal  and  binding 
material  rammed  hard  in  layers.  The  pig  is  melted  down 
with  addition  of  cinder.  The  cinder  is  then  taken  off,  the 
iron  piled  up  in  the  middle  of  the  hearth  and  melted  down 
again,  when  it  reposes  on  the  bottom  under  a  layer  of  slag. 
The  slag  is  again  removed,  and  the  bloom  taken  out,  hammered, 
etc.  The  product  is  apt  to  be  very  heterogenous ;  about  three- 
quarters  of  it  is  good  steel.  The  process  takes  about  2^  hours. 
The  blooms  are  cut  in  two,  and  reheated  separately  in  the  same% 
hearth. 

Fosberg's  Swedish  hearth  is  very  similar  to  the  ordinary 
Lancashire  hearth,  except  it  has  three  tuyeres  (one  at  the  back) 
instead  of  two,  and  also  an  adjustable  bottom  whose  height 
can  be  regulated  as  desired. 

Franche-Comte  process:  The  hearth  is  nearly  rectangular, 
and"  is  composed  of  cast-iron  plates;  it  is  closed,  and  the  bottom 
may  be  cooled  between  heats  with  water  underneath.  It  is 
provided  with  one  or  two  tuyeres,  and  the  blast  is  preheated 


CHARCOAL  HEARTH  PROCESSES        7  7 

by  the  products  of  combustion.  Pigs  of  gray  cast  iron  are 
melted  down  as  in  the  Swedish  Wallon  process,  i.e.,  are  grad- 
ually pushed  forward  as  their  ends  melt  otf.  This  continues  for 
about  90  minutes  or  less,  during  which  the  bloom  from  the 
preceding  charge,  having  been  cut  in  two,  is  reheated  in  the 
same  hearth,  and  forged,  three  heatings  and  forgings  being 
needed  for  each  half  bloom.  The  pasty  mass,  which  has  mean- 
while accumulated  on  the  hearth  bottom,  is  now  lifted  above 
the  tuyeres  and  gradually  melted  down,  falling  drop  by  drop 
past  the  tuyeres.  This  occupies  some  20  to  25  minutes  more. 
Those  parts  of  the  mass  resulting  from  this  second  fusion  which 
are  still  imperfectly  decarburized  must  be  raised  up  and  melted 
down  a  third  time  (Howe). 

The  J.  J.  Hudson  process,  recently  employed  in  this  country, 
consists  in  melting  the  charge  between  layers  of  charcoal  in  a 
specially  designed  furnace  of  the  open  hearth  type.  The  furnace 
is  preheated  by  means  of  oil  or  gas,  and  a  thick  bed  of  charcoal  is 
provided  upon  which  the  charge  of  pig  is  made.  By  the  intro- 
duction of  blasts  of  cold  air  through  tuyeres,  the  metal  is  melted 
and  boiled,  filtering  through  the  charcoal  which  consumes  the 
impurities,  eliminating  them  from  the  mollen  mass.  Charcoal 
may  be  added  at  any  time  during  the  heat  and  is  generally  added 
near  the  end  to  dispel  any  injurious  gases  that  may  arise,  thereby 
insuring  complete  purification  of  the  metal.  The  method  has  the 
effect  of  purifying  and  refining  the  iron  by  decarburization  and 
oxidation.  It  is  stated  that  it  may  be  applied  to  the  manufacture 
of  charcoal  steel  (higher  in  carbon)  with  equally  valuable  results. 
(Iron  Age,  4/18/12). 

In  the  Lancashire  process,  American  Lancashire  process,  and 
Swedish  Lancashire  process,  all  of  which  are  about  the  same, 
the  hearth  consists  of  unlined,  water-cooled,  cast-iron  plates,  and 
is  provided  with  two  (sometimes  only  one)  tuyeres.  The  blast 
is  somewhat  preheated  by  the  products  of  combustion.  If  not 
enough  slag  remains  from  the  last  operation  to  cover  the  bottom, 
some  is  added,  and  charcoal  is  piled  up  to  above  the  tuyeres.  On 
top  of  this  is  placed  the  pig  in  lumps  (sometimes  previously 
heated  in  the  same  hearth),  which  is  covered  with  charcoal  and 
the  blast  turned  on.  The  pig  melts  in  drops  which,  in  passing  the 
tuyere  area,  become  partially  decarburized  and  collect  on  the 
bottom.  When  it  is  all  melted,  it  is  worked  with  bars  so  it  will 
become  mixed  with  the  slag  and  be  thoroughly  purified.  When 
this  has  taken  place,  as  shown  by  the  fact  that  it  is  stiff  and  pasty 
the  mass  is  raised  above  the  tuyeres  and  melted  down  again  to 
free  it  from  the  intermingled  slag,  care  being  taken  that  this 
remelted  lump  is  not  cut  by  the  working  bars,  as  this  would  intro- 
duce fresh  slag.  The  lump  is  then  taken  from  the  furnace  and 
hammered,  etc.  The  operation  takes  about  iM  to  i%  hours. 
About  275  to  300  pounds  of  pig  are  used  for  a  charge.  A  modi- 
fication of  this  process  consists  in  simply  melting  soft  scrap, 
which  is  practically  the  last  stage  in  the  method  where  pig  is 
employed.  This  is  used  to  some  extent  in  this  country  for  mak- 
ing charcoal  sheets,  etc. 


78  CHARCOAL  HEARTH  PROCESSES 


Pi'i 
Tl 


The  Lombardy  process  has  the  peculiarity  of  subjecting  the 

>ig  to  a  special  refining  before  the  process  proper  commences. 

The  pig  is  charged  in  the  hearth  on  top  of  charcoal,  and  melted 
slowly  in  about  2}^  hours,  with  only  a  small  amount  of  blast. 

During  this  period  charcoal  is  thrown  on  occasionally,,  and 
each  time  this  is  done  the  pig  is  raised  up.  The  charcoal  is 
then  taken  out,  the  slag  chilled  with  water  and  removed,  and 
hammer  slag  mixed  with  the  molten  metal,  which  becomes  pasty 
and  is  taken  out  and  broken  up  into  six  pieces.  The  hearth  is 
then  cleaned  and  filled  with  powdered  charcoal  which  is 
thoroughly  stamped  down.  Each  of  the  pieces  of  metal  is  then 
melted  down  separately  with  slag  or  charcoal,  and  subsequently 
refined  as  usual.  The  time  required  for  the  entire  charge  is  not 
less  than  18  hours,  and  the  charcoal  required  amounts  to  about 
2^  times  the  weight  of  the  pig  (Percy). 

The  Paai  steel  process  is  very  similar  to  the  Carinthian.  The 
pig  is  melted  down  to  form  a  cake,  while  pieces  of  the  previous 
bloom  are  reheated  in  the  cinder  and  hammered.  The  bottom 
cake  is  then  exposed,  and,  if  already  hard  and  steely,  is  finished, 
but  if  otherwise,  it  must  be  further  treated.  For  this  purpose 
the  charcoal  is  renioved  from  the  hearth,  and  rich  scale  or  oxides 
are  stirred  into  the  iron  until  it  begins  to  get  hard,  when  the 
charcoal  is  put  back  and  the  metal  melted  down;  after  this  the 
bloom  is  hammered,  etc.  Some  of  the  metal  remains  in  the 
hearth,  and  forms  part  of  the  next  charge  (Percy). 

The  Rohnitz  process  resembles  the  Bohemian  most  nearly. 
Reheating  and  refining  operations  take  place  simultaneously 
in  the  same  hearth.  Mottled  or  even  gray  pig  is  used,  and 
the  metal  after  melting  down  is  treated  as  in  the  Lombardy 
process  (Percy). 

In  the  Salzburg  process  gray  pig  is  used,  which  is  subjected  to 
some  preliminary  treatment  as  in  the  Lombardy  process.  Re- 
heating and  refining  are  conducted  in  the  same  hearth,  but  the 
former  is  finished  before  the  latter  begins.  A  considerable  amount 
of  cinder  is  formed,  and  it  must  be  tapped  out  frequently. 

In  the  Siegen  process  the  bottom  of  the  hearth  is  formed  of 
a  mixture  of  crushed  cinder  and  hammer  slag.  Mottled  or 
white  pig,  in  long  pieces,  is  treated  exactly  as  in  the  Walloon 
process.  •  J  > 

In  the  Siegen  raw  steei  finery  process  the  hearth  is  much 
as  usual,  with  the  bottom  composed  of  pieces  of  fine-grained 
sandstone;  there  is  usually  one  tuyere.  The  blooms  are  cut 
in  pieces  and  reheated  in  the  same  hearth,  one  piece  being 
melted  down  with  the  next  charge.  The  pig  is  melted  down 
in  successive  portions,  on  top  of  the  charcoal,  and  rich  cinder 
is  thrown  in  to  oxidize  the  carbon;  if  this  action  has  gone  too  far, 
spiegel  is  added.  The  excess  of  cinder  is  tapped  off,  and  when 
the  ball  is  of  the  proper  size  and  consistency,  it  is  removed, 
hammered,  cut  up,  and  graded  by  fracture,  the  product  being 
heterogeneous.  One  charge  requires  about  7  to  8  hours. 

In  the  slag  bottom  process,  practised  in  Styria,  the  hearth 
is  similar  in  construction  to  the  Franche-Comte",  etc.  The 


CHARCOAL  HEARTH  PROCESSES  79 

bed  is  composed  of  rich  finery  cinder,  broken  up  small  and 
stamped  down  carefully.  White  pig  iron  is  used  in  small  pieces, 
which  are  melted  down  on  charcoal.  The  bloom  is  divided  into 
eight  pieces,  which  are  reheated  in  the  slag  in  the  same  hearth. 
A  charge  takes  about  i^  to  2  hours  (Percy). 

In  the  South  Wales  (South  Welsh)  process,  pig  iron  is  first 
melted  down  in  a  coke  refinery,  and  there  part  of  its  silicon  and 
carbon  are  removed  by  the  action  of  the  blast.  It  is  then  tapped 
out  into  a  pair  of  charcoal  hearths,  the  relatively  acid  slag  being 
held  back,  and  any  which  runs  into  the  charcoal  hearths  being 
carefully  removed.  The  partly  solidified  metal  is  broken  up  and 
piled  near  the  tuyere.  After  melting  down,  it  is  repeatedly 
raised  slightly  from  the  bottom,  apparently  as  in  the  Lancashire 
process.  The  slag  is  tapped  off  from  time  to  time.  As  soon  as 
the  metal  has  come  to  nature,  it  is  withdrawn  and  hammered 
(Howe).  When  the  metal  melts  down,  after  being  piled  up  in 
front  of  the  tuyere,  the  operation  of  working  it  is  termed  sink- 
ing a  lump  or  sinking.  The  last  cinder  solidifies  into  a  more  or 
less  cylindrical  piece,  hollow  in  the  center,  due  to  chilling  around 
the  point  of  a  bar  inserted  through  the  cinder  hole,  and  is  called  a 
fox  tail.  The  ball  is  hammered  into  oval  slabs  which  are  nicked 
in  seven  or  eight  places,  quenched  in  water,  and  broken  into 
pieces  called  stamps,  which  are  graded  according  to  their  frac- 
tures. These  are  reheated  in  a  furnace  called  a  hollow  fire 
which  has  two  chambers,  in  one  of  which  coke  is  burned,  and  in 
the  other  the  iron  is  heated  so  it  does  not  come  in  contact  with 
the  fuel,  but  only  with  the  gas.  The  stamps  are  laid  on  a  peel 
(staff),  the  blade  of  which  is  of  the  same  quality  of  iron.  After 
heating,  they  are  welded  together,  then  nicked  and  bent  over  so 
the  staff  material  forms  the  top  and  bottom. 

The  Knobbling  process  is  practically  identical  with  the  South 
Wales. 

Stridsberg's  hearth  is  provided  with  four  tuyeres  and  two 
working  doors  on  opposite  sides,  and  is  practically  a  double 
Lancashire  hearth. 

The  Styrian  charcoal  process  (Styrian  open  hearth)  employs 
the  ordinary  type  of  hearth.  The  bed  is  formed  of  small  pieces 
of  charcoal,  mixed  with  a  small  amount  of  cinder  from  the  pre- 
vious heat.  Reheating  and  refining  are  performed  simultane- 
ously in  the  same  hearth.  White  pig  iron,  in  small  pieces,  is 
slowly  melted  down  on  charcoal  in  two  portions;  this  is  arranged 
so  that  the  second  portion  shall  begin  to  melt  about  10  minutes 
after  the  commencement  of  the  first.  A  small  amount  of  hammer 
slag  is  thrown  on  the  melted  metal  which  has  previously  been 
denuded  of  charcoal.  The  bloom  is  cut  into  four  pieces  for 
subsequent  hammering,  etc.  A  heat  lasts  about  2  hours  (Percy). 

The  Styrian  raw  steel  process,  according  to  Tunner,  bears 
such  a  close  resemblance  to  the  preceding  that  it  is  difficult 
to^distinguish  between  them,  and  frequently  soft  iron  is  made  by 
this  process. 

The  Tyrol  process  closely  resembles  the  Styrian. 

The  Walloon  process,  or  Swedish  Walloon  process,  is  used 


8o  CHARCOAL  IRON— CHEMICAL  FORMULA 

in  Sweden  for  making  bars  to  be  converted  into  blister  steel. 
The  hearth  is  rectangular,  and  is  built  of  unlined,  water-cooled, 
cast-iron  plates,  and  is  provided  with  one  tuyere.  One  or  two 
very  long  pigs  of  white  or  mottled  cast  iron  are  melted  down 
drop  by  drop,  being  pushed  forward  as  their  ends  melt  off, 
till  enough  to  yield  a  bloom  of  from,  say,  84  to  93  pounds  has  been 
melted.  This  may  take  some  20  minutes,  during  which  the 
pasty  metal,  gradually  reaching  the  bottom  of  the  hearth,  is 
worked  constantly.  The  pasty  mass  is  now  broken  up,  raised 
above  the  tuyere,  and  melted  a  second  time,  apparently  much  as 
in  the  Lancashire  method.  During  this  time  the  bloom  from  the 
preceding  charge  is  heated  in  this  same  hearth,  held  steeply  in- 
clined (Howe). 

The  Eifel  Walloon  process  and  the  Styrian  Walloon  process 
appear  to  have  no  essential  differences  from  the  above. 

Charcoal  Iron. — (i)  Pig  iron  smeited  with  charcoal:  see  page  343; 
(2)  wrought  iron  made  by  some  charcoal  hearth  process  (q.v.),  or 
from  charcoal  pig:  see  page  379. 

Charcoal  Kiln.— See  Charcoal. 

Charcoal  Pig.- — See  page  343. 

Charcoal  Plate. — See  page  433- 

Charcoal  Refinery. — See  page  383. 

Charcoal  Retort.— See  Charcoal. 

Charcoal  Sheet. — See  page  433. 

Charcoal  Steel. — See  page  77- 

Charcoal  Wrought  Iron. — Wrought  iron  produced  by  some  char- 
coal hearth  process,  or  from  charcoal  pig. 

Charge. — (i)  In  a  blast  furnace,  the  amount  of  material  composing 
a  round;  (2)  in  other  furnaces,  the  total  amount  of  material  for  a 
heat. 

Charger. — In  the  crucible  process:  see  page  114. 

Charging  Box. — See  page  314. 

Charging  Door. — Of  a  furnace:  see  pages  182  and  183. 

Charging  Machine.— See  page  314. 

Charging  Tray. — Charging  box:  see  page  314. 

Charkt.  (obs.).' — An  old  English  name  for  a  kind  of  charcoal. 

Charles's  Law.— See  Gas. 

Charpy  Pendulum  Hammer;  Test.— See  page  482. 

Check  Analysis.— See  page  82. 

Checkers;  Checkerwork. — See  pages  203  and  311. 

Checking. — Cracking :  see  pages  56  and  1 10. 

Cheek. — See  page  297. 

Cheese. — See  page  61. 

Chemical  Action;  Affinity.— See  page  84. 

Chemical  Analysis. — See  pages  82  and  284. 

Chemical  Bond. — See  page  86. 

Chemical  Compound.— See  page  83. 

Chemical  Energy. — See  page  84. 

Chemical  Equation. — See  page  87. 

Chemical  Equivalent. — See  page  87. 

Chemical  Formula.— (i)  Meaning:  see  page  86;  (2)  for  physical 
properties:  see  page  337. 

'  " 


CHEMICAL  HARDENING— CHEMISTRY  8 1 

Chemical  Hardening. — See  page  69. 

Chemical  Hardness. — See  page  331. 

Chemical  Impurity. — See  impurity. 

Chemical  Metallurgy/ — See  Physical  Metallurgy. 

Chemical  Methods  of  Etching. — See  pages  286  and  287. 

Chemical  Passivity.— See  page  364. 

Chemical  Purity. — See  page  89. 

Chemical  Reaction,  Reagent. — See  page  86. 

Chemical  Solution. — See  pages  88  and  107. 

Chemical  Symbol. — See  page  86. 

Chemically  Dissolved/ — See  page  107. 

Chemistry. — Matter  is  anything  which  occupies  space.  It  is 
considered  made  up  of  very  small  particles  called  molecules  or 
atomic  aggregates,  which  again  are  composed  of  atoms.  A 
molecule  is  the  smallest  particle  of  matter  which  can  exist  in  the 
free  state,  and  an  atom  is  a  smaller  particle  which  enters  into 
chemical  combination.  This  constitutes  the  so-called  atomic 
theory  upon  which  chemistry  is  based.  Physics  is  concerned 
principally  with  the  relations  of  molecules,  and  chemistry  with 
the  relations  of  atoms.  Quite  recently  the  electron  theory  or 
electronic  theory  has  been  advanced  that  the  atom  is  not,  as 
formerly  assumed,  the  smallest  possible  unit,  but  is  itself  a  system 
consisting  of  a  nucleus  charged  with  positive  electricity  and  elec- 
trons, each  of  which  carries  the  minimum  unit  charge  of  negative 
electricity.  Meta -element  was  the  name  suggested  by  Crookes 
for  a  supposed  variety  of  an  element  whose  existence  was  indi- 
cated by  spectrum  analysis. 

There  are  three  states  of  matter :  the  solid,  the  liquid  and  the 
gaseous.  The  solid  state  is  due  to  the  strong  attraction  or 
cohesion  between  the  particles;  with  liquids  the  attraction  is 
much  less,  while  with  gases  there  is  a  repulsion.  Different, 
more  specific,  terms  have  been  adopted  to  indicate  changes 
affecting  the  state  or  condition  of  matter.  Transformation 
signifies  a  change  of  the  same  substance  from  one  form  to  another 
without  change  of  state,  as  in  the  case  of  allotropy;  a  special 
case  of  transformation  is  sometimes  known  as  transmutation, 
a  term  employed  by  the  alchemists  to  signify  the  change  of  one 
metal  into  another,  as  lead  into  gold;  conversion  is  still  used  in 
this  latter  sense,  as  in  the  conversion  of  pig  iron  into  steel. 
Transition  is  a  change  of  state  as  solid  to  gaseous.  Transference 
is  the  change  of  place  of  substances  or  forces,  as  the  point  at  which 
a  force  is  applied.  Translation  is  the  bodily  removal  of  a  sub- 
stance from  one  place  to  another.  Martens  uses  the  following 
terms  to  indicate  how  solid  material  may  be  brought  by  physical 
means  to  possess  the  desired  shape  or  form:  (i)  division: 
the  separation  into  different  parts,  as  by  cutting;  (2)  trans- 
formation :  changing  the  original  shape  without  separation,  as  by 
hammering;  (3)  agglomeration:  uniting  various  parts  into  one 
whole,  as  by  welding.  By  state  of  aggregation  is  understood 
the  different  conditions  in  which  matter  may  exist. 

Chemistry  is  divided  into  theoretical  or  pure,  which  deals  with 
the  underlying  laws  and  relations,  and  applied  or  technical  which, 


82  CHEMISTRY 

as  the  name  implies,  relates  to  its  commercial  application.  It  is 
usually  further  divided  into  organic  (the  chemistrv  of  compounds 
containing  carbon)  and  inorganic  chemistry  (the  chemistry  of 
compounds  which  do  not  contain  carbon),  but  the  line  is  not 
sharply  drawn.  These  again  are  divided  into  synthetic  (syn- 
thetical) and  analytical  (analytic)  chemistry,  the  former  having 
to  do  with  the  building  up  of  more  complicated  from  less  compli- 
cated substances,  while  the  latter  deals  with  the  determination  of 
the  components  of  a  substance.  Chemical  analysis  indicates 
that  the  analysis  is  by  chemical  methods  as  distinguished  from 
mechanical  or  microscopic  methods,  etc.  Analytical  chemistry 
is  subdivided  into  qualitative  analysis  (determining  only  the  con- 
stituents but  not  their  respective  percentages)  and  quantitative 
analysis,  where  both  the  constituents  and  their  respective  per- 
centages are  determined.  Quantitative  analysis  may  be  further 
divided  into  proximate  and  ultimate,  the  former  determining  the 
.  percentage  of  the  compounds  of  which  a  substance  is  made  up, 
while  the  latter  determines  the  percentage  of  the  elements;  e.g., 
the  proximate  analysis  of  coal  (that  almost  always  made)  shows 
the  percentages  of  volatile  matter,  fixed  carbon,  moisture, 
sulphur,  and  ash;  the  ultimate  analysis  of  the  same  sample 
would  show  the  percentages  of  hydrogen,  oxygen,  carbon,  nitro- 
gen, etc.  If  an  analysis  is  performed  with  the  aid  of  liquid 
solvents  and  reagents,  it  is  called  wet  or  humid  analysis  (process), 
while  if  dry  reagents  and  heat  are  employed,  it  is  called  dry 
analysis  (process),  and  this  latter  branch  of  chemistry,  including 
the  relations  of  reactions  to  the  evolution  (exothremic  reaction) 
or  the  absorption  of  heat  (endothermic  reaction),  is  termed 
thermochemistry  or  thermal  chemistry;  the  corresponding 
branch  of  metallurgy,  thermometallurgy ;  thermolysis  is  the 
analysis  or  dissociation  of  a  substance  by  the  application  of  heat 
alone.  The  analysis  of  ores  is  usuallv  termed  assaying,  which  is 
divided  into  wet  assaying  and  fire  assaying.  In  the  manufacture 
of  steel  a  ladle  analysis  is  that  made  from  drillings  from  a  small 
test  ingot  or  ingots  (ladle  test — in  England  termed  a  pit  sample) 
taken  during  the  pouring  of  each  melt.  A  finished  material 
analysis  is  one  made  on  a  sample  of  material  after  being  rolled  or 
otherwise  worked;  a  check  analysis  properly  means  a  duplicate 
determination  to  ascertain  or  confirm  a  previous  result,  but  is 
also  commonly  used  in  the  same  sense  as  finished  material  analy- 
sis and  as  distinguished  from  a  ladle  analysis.  A  residue  analy- 
sis is  one  made  on  what  remains  after  the  other  portion  of  a  sub- 
stance has  been  dissolved  away — the  method  followed  in  deter- 
mining the  composition  of  cementite  after  the  iron  matrix  has 
been  dissolved.  Spectrum  analysis  is  the  determination  of  a 
substance  or  of  its  constituents  by  the  color  of  its  "flame" 
when  heated  to  a  point  of  incandescence;  the  instrument  used  in 
this  work  is  termed  a  spectroscope.  Microchemisrry  is  where 
chemical  methods  are  employed  on  minute  substances  or  por- 
tions of  matter  in  conjunction  with  microscopical  methods.  In 
some  cases,  particularly  in  the  study  of  alloys,  it  is  desirable 
(owing  to  differences  in  atomic  weight)  to  express  composition 


CHEMISTRY  83 

as  atom  percent  instead  of  actual  weight  percent;  this  is  arrived 
at  by  a  proportion  between  the  respective  percentages  by  weight 
and  the  atomic  weights,  e.g.: 

Weight,  %  Atom,  % 

Coppet  (atomic  weight,     63.5)  90  94.4 

Tin         (atomic  weight,  118.0;  10  5.6 

If  the  molecules  of  a  given  substance  are  composed  of  similar 
atoms,  the  substance  is  called  an  element;  if  of  two  or  more  dif- 
ferent kinds,  a  compound  (chemical  compound).  A  mechanical 
mixture  (intimate  mixture)  is  where  two  or  more  substances  are 
in  a  very  fine  state  of  division,  and  very  intimately  mixed,  but  can 
be  separated  by  purely  mechanical  means,  e.g.,  a  mixture  of  iron 
filings  and  powdered  sulphur  can  be  separated  by  the  aid  of  a 
magnet.  A  compound  is  said  to  be  semi-combined  when  the 
constituents  are  only  loosely  held  together,  as  in  the  case  of 
water  of  crystallization.  While  atoms  are  too  small  .to  be 
measured  or  weighed  directly,  it  is  possible  to  compare  their 
properties  with  each  other,  and  their  relative  weights  are  called 
atomic  weights.  Formerly  these  weights  were  based  on  that  of 
hydrogen,  the  lightest  atom,  as  i;  the  present  standard  is  based 
on  a  weight  of  16  for  oxygen  as  this  gives  numbers  which  are 
somewhat  easier  for  calculations.  The  molecular  weight  in 
grams  is  called  the  gram  molecular  weight  (G.  M.  W.)  usually 
abbreviated  to  molar  weight  or  simply  mole.  In  chemical  work 
it  is  frequently  useful  to  make  up  what  are  known  as  standard 
solutions  which  contain  a  definite  amount  of  some  reagent;  a 
molar  solution  Contains  one  mole  of  solute  (dissolved  substance) 
per  liter  of  solvent;  a  normal  (N)  solution  is  one  which  contains, 
per  liter,  an  amount  of  the  substance  equal  to  the  mole  divided 
by  the  valence  or  basicity;  a  decinormal  or  tenth  normal  (N/io) 
solution,  for  example,  contains  one-tenth  this  amount.  The 
percentage  of  the  solute  is  often  referred  to  as  the  concentration. 
From  Avogadro's  law  (see  below)  it  is  evident  that  a  mole  of  any 
gas  will  occupy  the  same  volume  (22.4  liters  under  standard 
conditions  of  temperature  and  pressure) ;  this  is  known  as  a  gram- 
molecular  volume  (G.  M.  V.)  or  molar  volume. 

There  are  now  83  elements  recognized,  but  not  over  about 
half  are  of  common  occurrence  or  application;  these,  together 
with  their  symbols  and  atomic  weights  are  listed  in  the  accom- 
panying table.  Elements  are  classed  as  metals  and  non-metals, 
while  certain  ones  occupying  an  intermediate  position  are 
called  metalloids  (of  the  nature  of  metals).  Metals  have  a 
bright  appearance  or  metallic  luster,  at  least  when  freshly 
polished,  and  in  varying  degrees  the  properties  of  malleability, 
ductility,  etc.,  and  their  oxides  are  generally  basic;  the  non-met- 
als have  not  these  physical  properties,  and  their  oxides  are  gener- 
ally acid;  metalloids,  as  a  rule,  resemble  the  metals  in  their 
physical  properties  or,  as  in  the  case  of  carbon,  in  their  ability 
to  form  alloys  with  metals,  and  the  non-metals  in  their  general 
chemical  properties.  Following  the  classification  of  the  alche- 
mists, metals  are  still  referred  to  as  noble  or  base  (ignoble) ;  the 


84 


CHEMISTRY 


International  Atomic  Weights  (1917) 
Oxygen  =  16 


Element 

Sym- 
bol 

Atomic 
weight 

Element 

Sym- 
bol 

Atomic 
weight 

Aluminium.     .  . 

Al 

27  .  1 

Molybdenum  .  . 

Mo 

96  o 

Antimony 

Sb 

I2O    2 

Nd 

Argon  

A 

39.88 

Neon  

Ne 

20  2 

Arsenic 

As 

74  96 

Nickel 

Ni 

58  68 

Barium  
Bismuth  

Ba 
Bi 

137-37 
208.0 

Niton  (radium  emanation) 
Nitrogen  

Nt 
N 

222.4 
14  01 

Boron  
Bromine  
Cadmium  
Caesium  

B 
Br 
Cd 
Cs 

II.  0 

79.92 

I  I  2  .  4O 
132.81 

Osmium  
Oxygen  
Palladium  
Phosphorus  

Os 
O 
Pd 
p 

190.9 
16.00 
106.7 
31  04 

Calcium  ' 
Carbon  

Ca 

c 

40.07 
I2.OOS 

Platinum  
Potassium  

Pt 

K 

195.2 
39   10 

Cerium  
Chlorine  

Ce 

Cl 

140.25 

35  -46 

Praseodymium  
Radium  

Pr 
Ra 

140.9 
226  o 

Chromium  .      .  . 

Cr 

52    O 

Rhodium..  . 

Ph 

102    9 

Cobalt  

Co 

58.97 

Rubidium  

Rb 

85   45 

Columbium 

Cb 

93   I 

Ruthenium 

Ru 

101   7 

Copper  

Cu 

63.57 

Samarium  

Sa 

150  4 

Dysprosium. 

Dy 

162   5 

Scandium  . 

Sc 

44  I 

Erbium  
Europium.   . 

Er 
Eu 

167.7 
152  o 

Selenium  
Silicon.  .  .  . 

Se 
Si 

79-2 
28  3 

Fluorine  
Gadolinium  • 

P 

Gd 

19.0 
157   3 

Silver.  

Sodium  .  .  ',  . 

fc 

107.88 
23  oo 

Gallium  
Germanium 

Ga 
Ge 

69.9 
72   5 

Strontium  

Sulphur 

Sr 

s 

87.63 

32    06 

Glucinum  

Gl 

p.l 

Tantalum  

Ta 

181  .5 

Gold       .    . 

Au 

197    2 

Tellurium  . 

Te 

127  5 

Helium  
Holmium 

He 
Ho 

4.00 
163   5 

Terbium  
Thallium 

Tb 
Tl 

159-2 
204  o 

Hydrogen  

H 
In 

1.008 
1148 

Thorium  
Thulium  . 

Th 
Tm 

232.4 
1  68  5 

Iodine  

I 

126.92 

Tin  

Sn 

118.7 

Iridium 

Ir 

193   I 

Titanium 

Ti 

t8   I 

Iron  

Fe 

55  -84 

Tungsten  

W 

4.0 

Krypton 

Kr 

82  92 

Uranium 

u 

238  2 

Lanthanum  
Lead 

La 
Pb 

139.0 
207   2O 

Vanadium  
Xenon 

V 
Xe 

51.0 

I3O    2 

Lithium  

Li 
Lu 

6.94 
175  o 

Ytterbium  (Neoytterbium) 
Yttrium 

Yb 
Yt 

173-5 

88  7 

Magnesium 

Mg 

24.32 

Zinc  '  

Zn 

65  37 

Mn 

54  93 

Zirconium 

Zr 

90  6 

Mercury  

Hg 

200  .6 

base  metals  were  those  which  were  readily  dissolved  by  ordinary 
acids  or  solvents,  while  the  noble  metals  resisted  all  but  the  most 
powerful,  such  as  aqua  regia  ("royal  water")  a  mixture  of  about 
3  parts  of  hydrochloric  acid  and  i  part  of  nitric  acid. 

The  attraction  between  atoms  which  causes  them  to  combine 
to  form  a  molecule  is  called  chemical  affinity  (such  an  aggrega- 
tion of  atoms  and  their  mutual  attraction  is  sometimes  termed  as- 
sociation), and  the  cause,  chemical  atraction  or  chemical  energy. 
It  is  always  assumed  that  a  molecule  is  made  up  of  whole  atoms, 
and  not  of  fractions  of  an  atom.  The  folio  wing  are  the  funda- 
mental laws  with  regard  to  combinations  of  atoms:  constant 
proportions  or  definite  proportions:  A  given  compound  always 


CHEMISTRY  85 

contains  the  same  elements  combined  together  in  the  same 
proportion  by  weight.  Multiple  proportions  (Dalton's  law): 
When  the  same  two  elements  combine  together  to  form  more  than 
one  compound,  the  different  weights  of  one  of  the  elements  which 
unite  with  a  constant  weight  of  the  other  bear  a  simple  ratio 
to  one  another.  Reciprocal  proportions,  or  equivalent  propor- 
tions :  The  weights  of  different  elements  which  combine  sepa- 
rately with  one  and  the  same  weight  of  another  element  are  either 
the  same  as,  or  are  simple  multiples  of,  the  weights  of  these 
different  elements  which  combine  with  each  other.  Gaseous 
volumes  (law  of  Gay-Lussac):  When  chemical  action  takes 
place  between  gases,  either  elements  or  compounds,  the  volume 
of  the  gaseous  product  bears  a  simple  relation  to  the  volumes  of 
the  reacting  gases.  Other  basic  laws  are:  Avogadro's  law: 
Under  the  same  conditions  of  temperature  and*  pressure,  equal 
volumes  of  all  gases  contain  the  same  number  of  molecules. 
Dulong  and  Pettit's  law  of  atomic  heat  (only  approximately 
true):  The  product  of  the  atomic  weight  of  an  element  by  its 
specific  heat  is  a  constant  quantity  (approximately  6.4). 

In  1863-64  Newlands  found  by  arranging  the  elements  (omit- 
ting hydrogen)  in  the  order  of  their  atomic  weights  that  there 
was  a  recurring  similarity  in  their  characteristics;  what  is  known 
as  Newlands'  law  of  octaves  is  that  each  element  closely  resembles 
the  eighth  element  (counting  the  element  itself  as  one)  above  or 
below  it  in  the  scale.  There  is  some  difficulty  in  making  out  the 
scale  above  chlorine  (35.5),  which  was  largely  corrected  by 
Mendelejeff  in  1869:  Mendele Jeff's  periodic  law  is  that  all  the 
properties  of  the  elements  are  periodic  functions  of  their  atomic 
weights.  He  was  able  to  predict  certain  elements  unknown 
at  the  time,  and  to  foretell  with  an  astonishing  degree  of 
accuracy  what  properties  they  would  possess;  which  predictions 
were  notably  confirmed  in  the  cases  of  scandium,  gallium  and 
germanium. 

Isomerism. — All  bodies  of  identical  molecular  weight  were 
originally  termed  isomeric;  but  it  is  now  found  convenient 
(Thorpe)  to  restrict  this  term  to  bodies  which  not  only  possess 
identical  molecular  weights,  but  are  also  of  similar  chemical 
type,  and  possess  different  physical  and  chemical  properties. 
Proffessor  Howe  proposes  the  following  definition:  Isomerism 
is  a  change  in  the  properties  of  a  compound  without  change  of 
state  or  of  ultimate  composition.  It  is  habitually  accompanied 
by  a  change  in  internal  energy,  and  it  is  supposed  to  be  due  to 
a  change  in  the  number  or  in  the  arrangement  of  the  atoms  in 
the  molecule.  It  is  to  compounds  what  allotropy  is  to  elements 
(I.  A.  T.  M.). 

Metamerism  is  where  compounds  have  not  only  the  same  per- 
centage composition  but  also  the  same  molecular  weight.  Poly- 
merism  is  a  case  of  the  same  percentage  composition  but  different 
molecular  weights. 

One  atom  does  not  necessarily  combine  with  only  one  other 
atom;  it  may  combine  with  several,  or  several  of  the  same 
kind  may  be  needed  to  combine  completely  (saturate)  another. 


86  CHEMISTRY 

Hydrogen  and  certain  other  elements  which  have  the  smallest 
combining  power  (valence,  valency,  or  atomicity)  have  assigned  to 
them  a  value  of  i ;  they  are  said  to  be  monovalent  or  univalent 
atoms,  or  simply  a  monad.  To  make  this  clearer  it  is  assumed 
that  such  an  atom  has  a  single  bond  which  can  become  attached 
only  to  a  single  bond  of  another  atom.  Thus,  if  an  atom  has 
two  such  bonds,  it  can  become  attached  to  the  bonds  of  two 
monovalent  atoms,  or  of  one  divalent  atom.  Valences  are  ex- 
pressed as  follows: 

Name 
Valence  (noun)  (adjective) 

T  monad  monovalent  or  univalent 

II  dyad  divalent 

III  ,      triad  trivalent 

IV  tetrad  tetravalent  or  quadravalent 

V  pentad  pentavalent 

VI  hexad  hexavalent 

To  avoid  writing  the  name  of  an  element  in  full  each  time, 
abbreviations  of  the  name  (or  the  Latin  or  Greek  name),  called 
chemical  symbols,  are  employed.  The  symbol  for  an  element 
denotes  not  only  the  name,  but  also  one  atom,  the  atomic  weight, 
and  all  the  various  properties  which  it  possesses.  The  composi- 
tion of  a  substance  or  compound  represented  by  symbols  is  called 
its  formula  (chemical  formula).  Where  there  is  more  than  one 
atom  of  a  given  kind  in  a  molecule,  it  is  indicated  by  a  figure 
written  just  below  and  to  the  right  of  the  chemical  symbol;  thus, 
Fe2Os  shows  that  a  molecule  of  ferric  oxide  is  composed  of  two 
atoms  of  iron  (Fe)  and  three  atoms  of  oxygen  (O).  A  number 
written  immediately  in  front  of  such  a  formula,  and  on  the  same 
line,  applies  to  the  formula  as  a  whole;  thus,  3Fe2O3  represents 
three  molecules.  There  are  different  kinds  of  chemical  formula. 
The  one  described  above  is  that  ordinarily  referred  to  and  is  the 
simplest;  it  is  known  specifically  as  an  empirical  or  composition 
formula.  A  rational  or  constitutional  formula  indicates  the 
manner  in  which  a  compound  is  made  up;  thus  calcium  carbonate 

(CaCO3)   may  be  written   CaO-CO2  or  Ca<^T>C=  O.     This 

latter  form  indicates  the  valence  of  and  manner  of  joining  the 
several  atoms,  and  hence  is  termed  a  structural,  graphic,  linkage, 
or  valence  formula.  To  indicate  wherein  lies  the  difference  in 
properties  of  certain  compounds  (isomers  or  stereo  -isomers) 
which  have  the  same  composition  formula,  it  is  necessary  to 
resort  to  three-dimension  space,  and  hence  they  are  termed 
stereo-formulae;  the  special  branch  dealing  with  this  subject  is 
termed  stereo-chemistry. 

Chemical  Reactions. — When  two  or  more  different  molecules 
are  brought  together,  the  atoms  will  rearrange  themselves, 
provided,  under  the  given  conditions,  they  have  not  a  greater 
affinity  for  the  atoms  with  which  they  are  already  combined. 
This  rearrangement  is  called  a  reaction.  A  substance  which, 
when  added  to  another,  causes  a  reaction  is  called  a  reagent 


CHEMISTRY  87 

(chemical  reagent) ;  this  term  is  commonly  restricted  to  certain 
substances,  such  as  acids  and  standard  solutions,  constantly  in 
use  in  a  chemical  laboratory,  particularly  those  used  in  analytic  al 
work.  The  following  types  of  reactions  may  occur: 

1.  Synthetic  reaction :  Where  two  or  more  differe  nt  substances 
combine  to  form  a  single  substance,  as 

SO3  +  H2O  =        H2SO4 

sulphur  trioxide     water     sulphuric  acid 

2.  Analytical  reaction:  Where  one  substance  is  split  up  (by 
heat  or  otherwise)  into  two  or  more  different  substances,  as 

CaCO3  +  heat  =  CaO  +       CO2 

calcium  carbonate  calcium  oxide  carbon 

(limestone)  (lime)  dioxide 

3.  Metathetical   reaction:  Where    two    or    more    substances 
react  to  form  two  or  more  entirely  different  substances,  as 

FeS        +  Mn  MnS         ^  +       Fe 

iron    sulphide         manganese      manganese    sulphide      iron 

Catalysis  is  where  a  chemical  reaction  is  promoted  by  the  pr  es- 
ence  of  another  substance  (catalytic  agent  or  catalyst)  which, 
does  not  itself  take  part  directly,  but  remains  the  same  through- 
out, or  is  only  temporarily  affected. 

The  combining  weight  or  chemical  equivalent  is  the  atomic 
weight  divided  by  the  valence,  e.g., 

Name  Atomic  Weight  Valence  Combining  Weight 
Sodium  23  I  23 

Calcium  40  II  20 

The  atomic  volume  is  the  value  obtained  when  the  atomic  weight 
is  divided  by  the  specific  gravity.  It  is  sometimes  desired  (in 
considering  volume,  etc.)  to  ascertain  what  is  known  as  the  value 
of  one  or  more  elements  in  terms  of  another;  for  example,  the 
carbon  value  of  phosphorus  is  obtained  by  dividing  the  given 
percentage  of  phosphorus  by  31  (its  atomic  weight)  and  multiply- 
ing by  12  (the  atomic  weight  of  carbon). 

That  portion  of  a  molecule  which  enters  into  a  chemical  re- 
action is  termed  a  radical ;  if  it  is  a  single  atom,  such  as  Ca  or 
Na,  it  is  a  simple  radical ;  if  composed  of  two  or  more  atoms, 
acting  like  a  simple  body,  such  as  SCU  or  NH4,  it  is  a  compound 
radical. 

A  molecule  consisting  of  a  single  atom  is  said  to  be  monatomic ; 
a  molecule  or  a  radical  consisting  of  two 'or  more  atoms  is  poly- 
atomic, or  specifically  diatomic  (two),  triatomic  (three),  tetra- 
tomic,  (four),  etc.  With  regard  to  the  atoms  of  hydrogen  which 
are  replaceable  in  an  acid  by  basic  atoms  or  radicals  (its  basicity) 
the  terms  monobasic  (one),  bibask  or  dibasic  (two),  tribasic 
(three),  etc.,  are  used,  or  where  there  are  two  or  more,  the  general 
term  polybasic. 

A  substance,  usually  a  gaseous  element,  at  the  instant  of  its 
formation,  is  said  to  be  in  the  nascent  condition,  and  exerts  a 
stronger  action  than  when  in  its  ordinary  state,  probably  because 
it  is  in  its  atomic  and  not  in  its  molecular  form.  Solution 


88  CHEMISTRY 

(chemical  solution)  is  where  one  substance  is  dissolved  or  merged 
in  another  without  completely  losing  its  identity,  i.e.,  undergoing 
a  reaction  whereby  a  new  compound  is  formed.  Thus,  common 
salt  is  dissolved  by  water,  forming  a  solution,  but  it  still  answers 
to  the  regular  tests  for  salt,  and,  upon  evaporating  it  to  dryness, 
the  salt  is  found  to  be  the  same  as  before.  If,  while  a  substance 
is  in  solution,  another  substance  is  added  (or  certain  conditions 
are  changed)  with  which  the  first  reacts  to  form  a  new  insoluble 
compound,  the  action  is  known  as  precipitation  (throwing  out  of 
solution,)  and  the  insoluble  compound  is  called  a  precipitate. 

Compounds  are  ordinarily  classified,  according  to  their  proper- 
ties, into  acids,  bases,  and  a  combination  of  the  two,  salts. 
In  chemistry  acids  are  usually  defined  as  having  a  sour  taste, 
having  the  property  of  turning  blue  litmus  paper  red,  etc.,  while 
the  bases  have  opposite  properties;  but  in  metallurgy,  acids  may 
be  considered  to  be  the  oxides  of  the  non-metallic  elements,  while 
bases  are  the  oxides  of  the  metallic  elements.  A  salt  is  neutral, 
or  either  slightly  acid  or  basic  in  its  properties.  Oxidation  is  the 
name  given  to  any  process  where  oxygen  combines  with  an  ele- 
ment or  substance;  the  opposite  of  this,  or  the  removal  of  oxygen, 
is  reduction. 

The  combination  of  two  different  elements  is  called  a  binary 
compound ;  of  three,  a  ternary  compound ;  of  four,  a  quaternary 
compound,  etc.  In  a  binary  compound,  usually  formed  of  a 
metallic  and  a  non-metallic  element,  the  name  of  the  latter  ends 
in  -ide,  thus,  sodium  sulphide,  calcium  oxide,  etc.  Where  two 
elements  combine  in  more  than  one  proportion,  it  is  necessary  to 
indicate  the  ratio  by  giving  the  number  of  atoms  of  the  variable 
(in  some  cases  of  both) : 

502  Sulphur  dioxide 

503  trioxide 

S2O3  sesquioxide  or  disulphur  trioxide. 

Some  elements  have  two  or  even  three  different  valences,  and 
it  is  essential  to  show  which  one  exists  in  a  given  compound. 
To  do  this,  the  suffixes  -ous  and  -ic,  for  the  lower  and  the  higher 
respectively,  are  used,  and  where  there  are  more  than  two 
arrangements,  the  prefixes  hypo-  for  the  lower  and  per-  or  hyper- 
for  the  higher,  are  also  employed.  Acids  are  designated  thus, 
and  the  salts  which. they  form  have  the- suffix  -ous  changed  to 
-ite,  and  -ic  changed  to  -ate,  the  prefix  (if  any)  remaining  un- 
changed. Examples  of  the  above  are: 

Acid  Salt  (of  sodium) 

Formula  Name  Formula  Name 

H2S2O4  hyposulphurous  acid  Na2S2O4   sodium  hyposulphite 
H2SO3    sulphurous  "      Na2SO3        "         sulphite 

H2SO4    sulphuric  "      Na2SO4        "         sulphate 

H2SO5   persulphuric  Na2SO5        "         persulphate 

While  an  acid  does  not  necessarily  contain  oxygen  (as  was  at  ' 
first  believed),  the  majority  do.     Those  oxides  which  combine 
with  water  to  form  acids  are  called  anhydrides;  thus,  SO2, 
sulphurous  anhydride,  SO3,  sulphuric  anhydride,  CO2,  carbonic 


CHENOT  PROCESS— CHESTNUT  COKE  89 

anhydride  (also  called  carbonic  acid,  but  really  incorrectly), 
etc. 

Dissociation  (dissociation  theory  is  (i)  the  temporary  decom- 
position of  a  substance  by  the  application  of  heat,  the  original 
substance  being  again  formed  upon  cooling;  the  temperature  at 
which  this  occurs  is  called  the  dissociation  point.  (2)  In  a 
liquid  or  molten  solution  it  is  the  separation  of  the  dissolved 
substance  (or  a  part  of  it)  into  electrically  positive  and  negative 
particles  or  radicals,  termed  ions  (ionic  theory)  which  remain 
loosely  bound  together  by  their  mutual  attraction;  this  is  called 
ionic  or  electrolytic  dissociation,  and  the  solution  an  electrolyte. 
If  a  suitable  electric  current  is  passed  through  the  solution,  this 
attraction  is  destroyed  and  the  electronegative 'ions  (anions)  go 
to  the  positive  pole  (anode)  where  their  negative  charge  is  neu- 
tralized and  they  appear  in  the  free  state  (no  longer  as  ions); 
similarly  the  electropositive  ions  (cations  or  kations)  go  to  the 
negative  pole  (cathode  or  kathode).  This  process  is  termed 
electrolysis  or,  in  the  cases  of  a  fused  electrolyte,  pyroelectrplysis. 
E.  D.  Campbell  suggests  the  term  ionid  in  place  of  ion  in  the 
case  of  metallic  solutions.  Electrolysis  is  based  on  the  following 
laws  or  assumptions :  Faraday's  laws :  the  amount  of  an  electro- 
lyte which  is  decomposed  is  proportional  to  the  quantity  (num- 
ber of  coulombs)  of  electricity  which  passes  through  it;  (2)  the 
weight  of  any  ion  liberated  by  a  given  quantity  of  electricity 
is  proportional  to  the  chemically  equivalent  mass  of  the  ion. 
The  electro-chemical  equivalent  of  an  element  or  substance  is  the 
amount  set  free  per' coulomb  of  electricity.  According  to  Arrhe- 
nius'  theory,  the  passage  of  an  electric  current  through  an  elec- 
trolyte is  by  means  of  the  motion  of  the  ions.  The  binary  or 
dualistic  theory  is  that  every  definite  compound  is  possessed  of 
equal  amounts  of  positive  and  negative  electricity.  Decomposi- 
tion is  the  splitting  up  of  a  compound  by  heat  or  some  other 
means;  it  is  broader  than  dissociation  in  that  decomposed  com- 
pounds need  not  necessarily  recombine  if  the  former  conditions 
are  restored. 

To  indicate  the  purity  of  chemicals,  various  designations  have 
been  adopted  (as  shown  on  the  labels  or  elsewhere)  which  are 
generally  rated  in  the  following  decreasing  order  of  excellence: 
(a)  strictly  chemically  pure:  guaranteed  to  contain  not  over 
.  .  .  percent  of  ...  (substance);  (6)  strictly  or  absolutely 
pure;  (c)  chemically  pure  (c.p.);  (d)  pure;  (e)  commercial;  (/) 
no  qualification.  It  should  be  noted  that  in  technical  writings 
it  is  usually  understood  that  only  high  quality  substances  are  in- 
tended, or  else  the  particular  grade  is  indicated  by  the  context 
or  the  purpose  in  question. 

Chenot  Process. — See  page  139. 

Chernoff  Process. — Of  treating  castings:  see  page  62. 

Cherry -red  Heat. — Color  temperature:  see  page  210. 

Chesterfield  Process. — See  page  229. 

Chestnut. — See  page  315. 

Chestnut  Coal.— See  Coal. 

Chestnut  Coke.— See  Coke. 


go  CHILL  CAST  PIG— CHROMOMETER 

Chill  Cast  Pig.— See  page  342. 

Chill  Mold. — See  page  300. 

Chill  (Chilled)  Roll.— See  page  403. 

Chill  Test. — For  charcoal  iron:  see  page  350. 

Chilled  Casting.— See  page  58. 

Chilled  Heat.— See  Ladle. 

Chipping. — Employed  to  remove  seams  and  other  surface  defects 
occurring  on  billets,  etc.  The  conditions  to  be  observed  are  that 
the  depth  shall  not  be  too  great,  that  the  opening  shall  be  flared, 
i.e.,  much  wider  than  deep,  and  that  no  sharp  cuts  shall  occur,  so 
that  after  rolling  or  forging  no  laps  or  lap  seams  will  result. 
Spot  Chipping.is  chipping  at  intervals  along  a  seam,  etc.,  to  test 
its  depth,  but  where  the  defect  need  not  be  removed  by  those 
means,  as  when  the  material  is  to  be  machined. 

Chipping  Face ;  Piece ;  Strip. — See  page  58. 

Chisel  Temper.— See  Temper. 

Chock. — See  page  406. 

Choking. — In  a  rolling  mill  with  grooved  rolls,  overfilling  a  pass. 

Chondrite,  Chondrule,  Chondrus. — See  page  292. 

Chromate  Ore. — See  page  244. 

Chromated  Steel. — See  page  451. 

Chromatic  Protection. — See  page  364. 

Chromatic  Thermometer. — See  page  205. 

Chrome. — See  Chromium. 

Chrome  Brick. — See  page  398. 

Chrome  Iron  Ore. — (i)  As  an  ore:  see  page  244;  (2)  as  a  refrac- 
tory: see  page  398. 

Chrome  Steel. — See  page  451. 

Chromeisen. — See  page  352. 

Chromic  Iron. — See  page  244. 

Chromite. — (i)  As  an  ore:  see  page  244;  (2)  as  a  refractory:  see 
page  398. 

Chromium. — Also  called  chrome;  Cr;  at.  wt,  52;  melt,  pt,  1515°  C. 
(2759°  F.);  sp.  gr.,  6.92.  It  is  not  found  free  in  nature;  its  chief 
occurrence  is  as  an  oxide  in  combination  with  iron,  etc.,  called 
chrome  iron  ore  (see  page  244).  The  pure  metal  is  hard,  of  a 
steel-gray  color,  and  is  not  readily  oxidized.  It  alloys  with  iron 
in  all  proportions,  and  is  obtained  principally  as  ferro-chrome 
(see  page  352).  Steel  of  which  it  is  a  constituent  is  called  chrome 
steel  (see  page  451).  It  raises  the  saturation  point  of  iron  for 
carbon  even  more  powerfully  than  manganese  does,  and,  like 
manganese,  prevents  the  separation  of  graphite.  For  influence 
on  corrosion:  see  page  367. 

Chromium  Carbide. — See  page  279. 

Chromium  Steel. — See  page  451. 

Chromo-ferrite. — See  page  272. 

Chromometer. — An  apparatus  used  in  chemical  analysis  for  deter- 
mining percentages  by  the  color  method.  It  consists  essentially 
of  two  graduated  tubes  containing  respectively  solutions  of  the 
standard  and  the  test  similarly  treated.  From  the  relative 
lengths  of  the  two  columns  when  they  have  the  same  color,  the 
percentage  is  found. 


CHUBB'S  METHOD— CLOSE  ANNEALING  91 

Chubb's  Method.— Of  percussive  welding:  see  page  504. 

Chuck. — See  page  406. 

Chute.— See  Billet  Chute. 

Chute  Process. — See  page  385. 

Cinder. — See  Slag. 

Cinder  Bottom. — See  Lining. 

Cinder  Dump. — A  place  for  the  disposal  of  waste  cinder. 

Cinder  Fall  (obs.). — In  an  old-style  blast  furnace,  the  plate  over 

which  the  cinder  runs  from  the  cinder  notch. 
Cinder  Heat.— See  Wash  Heat. 
Cinder  Inclusion. — See  page  57. 
Cinder  Iron;  Pig. — See  page  343. 
Cinder  Notch. — See  page  32. 
Cinder  Pit. — See  page  312. 
Cinder  Plate. — See  page  135. 
Cinder  Pocket. — See  page  311. 
Cintering. — Sintering.  • 

Circular  Inch. — The  area  of  a  circle  of  i"  diameter  =  0.7854  sq.  in. 
Circular  Mil;  Circular  Mil  Gage. — See  page  187. 
Cire  Perdu  Process.— See  page  301. 
Cito-ductile. — See  page  331. 
Clamps. — (i)  Of  a  crucible  furnace:  see  page  114;  (2)  of  a  testing 

machine:  see  page  469. 
Clapp-Griffith  Converter. — See  page  23. 
Class. — Of  steel:  see  page  455. 
Claudius  Process. — See  page  368. 
Clay.— See  page  396. 
Clay  Crucible. — See  page  -in. 
Clay  Dinas  Brick. — See  page  395. 
Clay  Ironstone  (Eng.). — See  page  244. 
Clay  Process. — See  page  139. 

Clayband;  Clayband  Ironstone  (Eng.). — See  page  244. 
Clean. — (i)  To  remove  the  scale  from  a  reheated  piece  of  steel; 

(2)  a  surface  free  from  scale;  (3)  of  castings:  see  page  58. 
Clean  Gas.— See  page  33. 
Clear  (verb). — See  page  376. 
Clearer.— See  page  415. 

Cleavage;  Cleavage  Brittleness. — See  page  123. 
Cleavage  Foliation. — See  page  124. 
Cleavage  Plane. — See  pages  123  and  282. 
Cleavage  Structure. — See  page  127. 
Cleavage  in  Traces. — See  page  124. 
Cleavage  Weakness. — Seepage  123. 
Clemandot  Process. — See  page  229. 
Clinker. — See  Slag  Cement. 
Clinkering. — See  page  44. 
Clinking  (Eng.). — See  page  223. 
Clinks  (Eng.). — Fractures  (cracks)  due  to  uneven  contraction  or 

expansion  of  large  masses. 
Clinorhombic  (Clinorhomboidal)  System. — Of  crystallization :  see 

page  120. 
Close  Annealing. — See  pages  232  and  431. 


92  CLOSE-GRAINED  IRON— COAL 

Close-grained  Iron ;  Close  Iron. — See  page  343. 

Close-jointed  Skelp. — See  page  489. 

Close  Order  in  Line. — See  page  283.  L 

Close  Pig.— See  page  343. 

Close-top  Mold. — See  page  299. 

Closed  Front. — See  page  32.    ' 

Closed  Guide. — See  page  416. 

Closed  Hearth. — See  pages  32  and  75. 

Closed  Pass. — See  page  405. 

Closed  Top. — (i)  Of  a  blast  furnace:  see  page  33;  (2)  of  a  mold: 
see  page  299. 

Closer. — See  page  405. 

Clot  (Eng.).— Rabble. 

Clotting. — The  sintering  or  semi-fusion  of  ores  during  roasting 
(Raymond). 

Coagulation. — Incipient  fusion  of  ores  which  are  being  roasted  or 
calcined  (something  to  be  guarded  against). 

Coal. — A  stratified,  combustible,  carbonaceous  mineral  result- 
ing from  the  decomposition  of  wood,  usually  accompanied  by 
heat  and  pressure.  Coals  are  usually  classified  according  to 
(a)  the  amount  of  volatile  matter  they  contain,  and  (6)  the 
purpose  for  which  they  are  suitable. 

Lignite  or  brown  coal  is  the  softest  variety,  somewhat  resem- 
bling peat,  and  is  high  in  volatile  matter  and  water.  It  is  not 
much  used  for  metallurgical  purposes.  It  kindles  easily,  has  a  long 
smoky  flame,  low  calorific  power,  and  does  not  coke.  Following 
is  the  usual  range  in  composition: 

Volatile  matter 40  to  54% 

Coke 60  to  46 

Fixed  carbon 51  to  36 

Ash i  to  10 

Sulphur up  to  3 

Moisture i  to  25 

A  variety  of  brown  coal,  altered  by  faulting  of  igneous  rocks, 
varying  in  composition  from  that  of  ordinary  brown  coal  to 
that  of  anthracite,  is  known  as  glance  coal. 

Bituminous  coals,  sometimes  called  soft  coals,  are  easily  the 
most  important  variety,  as  either  in  their  natural  condition, 
or  as  the  basis  of  artificial  fuels,  they  are  the  kind  usually  em- 
ployed for  heating  purposes.  They  burn  with  a  yellow,  lumin- 
ous, smoky  flame.  If,  upon  distillation  of  the  volatile  matter, 
they  melt  down  and  yield  a  hard,  strong,  coherent,  carbonaceous 
residue,  they  are  termed  coking  or  caking  coals  (rarely  binding 
coals  or  fat  coals);  otherwise,  non-coking  or  non-caking  coals 
(rarely  dry  coals) .  To  which  variety  a  coal  belongs  is  determined 
by  making  a  practical  test,  as  the  composition  or  appearance  is 
not  a  sufficient  indication.  Gas  coals  are  those  which  contain 
a  large  amount  of  volatile  matter,  and  yield  up  to  10,000  or 
12,000  cubic  feet  of  gas  per  ton.  Cannel  coal  (the  name  is  a 


COAL  APPLES— COAL  FURNACE  93 

corruption  of  "candle")  is  valuable  for  this  purpose,  but  differs 
somewhat  in  structure  and  appearance;  the  volatile  matter  may 
amount  to  over  70%;  on  heating,  it  splits  with  a  decided  cleavage, 
and  as  it  emits  a  cracking  sound,  it  is  sometimes  called  parrot 
coal.  Furnace  coal  is  any  sort  suitable  for  heating  purposes,  and 
the  term  manufacturing  coal  (Eng.)  is  used  in  the  same  sense. 
Forge  coal  or  smith  coal  is  the  kind  used  for  smiths'  forges; 
when  freshly  put  on  it  is  sometimes  termed  green  coal.  Bi- 
tuminous shale  is  a  grade  containing  a  large  amount  of  ash  and 
occurring  in  laminated  masses.  A  coal  very  low  in  volatile  mat- 
ter is  sometimes  called  lean  or  meager  coal;  the  term  is  usually 
applied  relatively  to  bituminous  coal.  Splint  coal  is  a  variety 
of  non-caking  coal  used  to  a  limited  extent  in  blast  furnaces 
in  Scotland. 

Following  is  the  approximate  range  in  the  composition  of 
bituminous  coals: 

Volatile  matter 20  to  35  % 

Coke 80  to  65 

Fixed  carbon 60  to  75 

Ash i  to  10 

Sulphur i  to     7 

Moisture •  o  to     7 

Anthracite  (hard  coal),  as  found  in  eastern  Pennsylvania, 
is  very  low  in  volatile  matter;  anthracite  coals  (sometimes 
termed  anthracite  in  England)  are  usually  somewhat  higher 
in  volatile  matter.  This  variety  is  hard  to  ignite,  and  it  burns 
with  very  little  flame.  Its  composition  is  approximately: 

Volatile  matter 3  to     7% 

Fixed  carbon 85  to  90 

Ash 3  to  7 

Sulphur up  to  i .  5 

Moisture o  to  4 

Occasionally  specimens  of  anthracite  are  found  in  spheroidal 
masses,  termed  coal  apples. 

Coal  as  mined,  occurring  in  large  and  small  lumps,  is  called 
run-of-mine  coal.  After  washing  and  crushing,  it  is  sorted 
into  sizes  which  receive  various  names  (according  to  their  size) 
such  as  buckwheat,  pea,  and  chestnut  or  nut.  The  fine  material 
containing  a  little  dirt,  which  is  removed  from  the  larger  pieces 
by  screening,  is  termed  slack.  In  the  anthracite  regions,  such 
coal  thrown  on  the  dump  is  called  culm. 

Pit  coal  is  an  old  English  name  for  mined  coal  (in  contra- 
distinction to  charcoal) ;  if  transported  on  vessels,  it  was  known 
as  sea  coal.  Coal  high  in  sulphur  is  sometimes  called  sulphur 
coal  or  stinking  coal. 

Coal  Apples.— See  Coal. 

Coal  Furnace. — See  pages  39  and  181. 


94  COAL  GAS— COIL 

Coal  Gas. — The  gas  obtained  by  the  distillation  of  bituminous 
coal  in  closed  retorts,  and  used  principally  for  illuminating 
purposes. 

Sexton  gives  an  average  analysis  (by  volume)  as: 

Hydrogen . . : 48% 

Carbon  monoxide 8 

Methane 36 

Ethylene 3.8 

Non-combustible 4.2 

Coalescence. — See  page  120. 

Coalite. — A  trade  name  for  a  product  obtained  by  filling  flat  rec- 
tangular retorts  with  bituminous  coal,  and  heating  vertically  in  a 
gas-fired  furnace  at  800°  F.  (425°  C.),  the  coal  swelling,  and  the 
resulting  pressure  giving  good  density  to  the  product.  It  resem- 
bles coke  in  appearance,  but  is  higher  in  volatile  matter,  and 
its  calorific  power  is  stated  to  be  close  to  that. of  coal;  it  is  also 
claimed  to  be  smokeless. 

Coarse-grained  Fracture. — See  page  178. 

Coating. — (i)  For  protection:  see  page  370;  (2)  in  wire  drawing: 
see  page  507. 

Cobalt.— Co;  at.  wt,  59;  melt,  pt.,  1464°  C.  (2667°  F.);  sp.  gr., 
8.72.  It  is  not  found  in  the  uncombined  state,  and  is  usually 
associated  with  nickel.  It  is  a  hard  white  metal  having  a  slight 
bluish  tinge.  For  influence  on  corrosion :  see  page  366. 

Cobalt  Steels. — See  page  453. 

Cobbing.— See  Ore. 

Cobble. — (i)  In  puddling:  see  page  377;  (2)  in  rolling:  see  page 

4i5. 

Cod. — See  page  299. 
Coddle. — Of  blast:  see  page  35. 
Codonoid. — See  page  290. 
Codorus    (obs.). — Or  silicon   ore:  a   silicious   iron  ore   formerly 

sometimes  used  in  puddling. 
Coefficient  of  Corrosion. — See  page  108. 
Coefficient  of  Distribution. — See  Solution. 
Coefficient  of  Elasticity. — See  page  334. 
Coefficient  of  Impact. — See  page  481. 
Coefficient  of  Restitution. — See  page  478. 
Coffee-mill  Squeezer. — See  page  377. 
Coffin  Bend. — See  page  265. 
Coffin  Joint;  Weld.— See  page  503. 
Coffin  Process. — For  axles  and  rails:  see  page  233. 
Cogging. — See  pages  115  and  407. 
Cogging  Hammer. — See  Hammer. 
Cogging  Mill. — See  page  411. 
Cohenite. — See  page  292. 
Cohesion. — See  page  81. 
Coil. — A  roll  or  bundle  of  wire,  hoop,  etc.,  made'up  in  this  form  for 

convenience  in  handling  and  shipping.     If  the^material  is  bent 


COKE  95 

backward  on  itself,  like  a  flattened  letter  "S,"  it  is  called  a 
scroll  bundle  or  hoop.  If  one  length  is  wound  up  on  itself,  like 
a  clock  spring,  it  is  known  as  a  single  coil  or  single  strand  (strip) 
coil;  if  several  lengths  are  thus  wound  up  simultaneously,  a 
standard  or  regular  coil ;  continuous  coils  are  made  up  of  several 
strips,  one  being  coiled  up  before  the  next  is  put  on,  with  a  short 
lap,  so  that  one  length  can  be  used  without  disturbing  the  re- 
mainder of  the  coil.  Coils  are  sometimes  called  strips.  A  hank 
is  a  bundle  of  wire;  a  stone  is  a  name  rarely  applied  to  a  bundle 
of  small  wire  weighing  about  12  pounds.  The  term  stone  wire 
is  usually  applied  to  fine  wire  suitable  for  wire  cloth  and  similar 
purposes. 

Coke. — Grade  of  tin  plate:  see  page  433. 

Coke. — (i)  The  residue  obtained  by  driving  off  all,  or  nearly  all, 
the  volatile  matter  from  solid  or  liquid  fuels;  (2)  as  generally 
understood,  such  residue  obtained  from  certain  kinds  of  bitumi- 
nous coals,  which  is  hard,  strong  and  porous,  and  hence  can 
support  a  heavy  burden  without  crushing.  This  latter  is  par- 
ticularly valuable  for  heating  by  contact,  as  it  has  practically  no 
flame.  As  its  specific  gravity  is  about  0.9,  while  that  of  carbon 
is  2,  over  50%  of  its  volume  must  be  air  space  which  enables  it 
to  burn  more  readily.  It  is  stated  (Bull.  No.  382,  U.  S.  Geol. 
Sur.)  that  the  coking  properties  of  a  coal  are  determined  by  the 
ratio  of  hydrogen  to  oxygen  in  the  composition  of  the  coal. 
Experiments  indicated  that  with  H:O  over  .50%  it  will  coke. 
Practical  tests  should,  however,  be  made. 

An  average  analysis  of  Connellsville  coke,  and  the  coal  from 
which  it  is  made,  is  as  follows: 

Coke,  %  Coal,  % 

Moisture —  1.33 

Volatile  matter 1.50  28.36 

Fixed  carbon 88 . oo  62.64. 

Sulphur 0.90  •       i. in 

Phosphorus 0.077  0.013 

Ash 10.50  7.68 

At  the  present  time  coke  is  made  in  either  beehive  or  retort 
ovens,  the  product  being  termed,  respectively,  beehive  coke, 
and  retort  coke  or  by-product  coke. 

Beehive  ovens  are  of  the  shape  which  their  name  indicates, 
and  are  built  either  in  a  single  row  against  a  hillside  (bank  ovens), 
or  in  a  double  row  back  to  back  (block  ovens).  They  are  of  fire- 
brick, faced  with  stone,  and  each  has  an  opening  in  the  top  for 
charging  (trunnel  head)  and  another  at  the  bottom  for  drawing 
(door).  They  are  usually  10^  to  12  feet  in  diameter.  The  charge 
amounts  to  about  4^  tons  for  forty-eight  hour  coke,  and  6  tons 
for  seventy -two  hour  coke,  these  two  names  indicating  the  length 
of  time  required  for  the  operation.  After  dumping  in  the  ovens, 
the  coal  is  leveled  off,  and  the  door  bricked  up  except  for  small 
openings  to  admit  the  air  for  combustion.  The  oven,  hot  from  a 
previous  charge,  or  heated  with  fuel,  causes  the  volatile  matter  to 


96  COKE 

be  driven  off;  this  burns  and  supplies  the  requisite  amount  of 
heat;  the  coking  proceeds  from  the  top  downward.  When  the 
process  is  complete,  the  red-hot  mass  is  quenched  with  water, 
broken  up  and  removed  from  the  oven  either  by  hand  with  rabbles 
or  by  a  machine  termed  a  coke  extractor  or  coke  pusher. 
Properly  burned  coke  usually  has  a  whitish  deposit  extending 
downward  from  the  top  a  couple  of  inches,  called  whiskers,  which 
is  supposed  to  be  an  indication  of  its  good  quality. 

In  retort  ovens  the  coal  is  placed  in  vertical,  or  horizontal, 
closed  brick  chambers  externally  heated  by  flues.  The  volatile 
matter  consisting  of  hydrocarbons,  tar,  and  ammonia  is  saved, 
for  which  reason  this  type  is  known  as  a  by-product  oven. 
The  by-product  recovery  operation  is  briefly  as  follows  (Meissner, 
Am.  I.  &•  S.  Inst.,  1913):  In  the  indirect  process  (indirect  re- 
covery process)  the  gas  leaves  the  ovens  through  the  foul  gas 
main,  located  above  the  ovens,  and  is  taken  to  the  by-product 
plant  where  it  is  cooled,  the  tar  extracted,  the  naphthalene  thrown 
down  as  far  as  possible,  and  the  ammonia  scrubbed  out  of  the  gas 
by  passing  through  water  towers  or  other  apparatus.  The 
weak  ammonia  liquor  is  passed  into  lead-lined  saturators  con- 
taining sulphuric  acid,  and  ammonium  sulphate  formed,  or  the 
distilled  ammonia  is  placed  in  tanks  and  shipped  as  strong  ammo- 
nia liquor.  In  the  direct  recovery  process  the  scrubbing  of  the 
ammonia  from  the  gases  is  avoided  by  passing  them  through 
the  saturator  after  the  separation  of  the  tar.  In  some  of  the  so- 
called  direct  processes  tar  is  separated  by  cooling  the  gases,  and 
in  this  case  a  certain  proportion  of  ammonia  is  precipitated  with 
the  tar  and  must  be  distilled.  In  others,  tar  is  separated  without 
the  precipitation  of  ammonium  salts.  These  latter  are  more 
properly  called  direct  than  those  where  some  of  the  am- 
monia is  precipitated,  which  should  be  called  semi-direct  proc- 
esses. The  thio -sulphate  process  is  the  name  usually  given  to 
a  process  for  utilizing  the  sulphur  contained  in  the  gases;  e.g., 
in  the  Burkheiser  process  a  special  oxide  purifier  removes  hydro- 
gen sulphide  from  the  gas  and  employs  it  to  make  an  acid  solu- 
tion for  the  recovery  of  ammonia  as  sulphate  and  sulphite. 
Where  the  surplus  gas  (after  extraction  of  the  by-products  and 
the  heating  of  the  retorts)  is  used  for  generating  power,  it  is 
called  a  waste  heat  oven ;  otherwise,  where  gas  is  sold,  as  much  as 
possible  is  generally  desired  for  that  purpose. 

Foundry  coke. — This  coke  is  selected  from  ovens  which  have 
burned  72  liours.  It  is  always  made  on  Mondays  and  Tuesdays, 
as  no  work  is  done  at  the  ovens  on  Sundays.  It  may  be  made  on 
other  days  of  the  week  by  shutting  down  another  day.;  It  is 
hard  and  large,  and  has  a  bright  appearance  caused  by  the  carbon 
condensing  on  the  surface.  This  coke  is  used  in  cupolas  for 
melting  iron,  and  also  for  heavy  forging  work. 

Furnace  coke  (blast  furnace  coke). — This  is  coke  that  is 
burned  48  hours,  and  is  used  in  smelting  ores  in  blast  furnaces. 
It  is  sometimes  used  in  cupola  practice. 

Standard  foundry  and  furnace  coke. — Sulphur  under  i%: 
the  lower  the  better.  Ash  not  over  13%;  the  quality  improves 


COKE  BARS— COLD  BENDING  97 

with  the  reduction  in  ash  until  the  percentage  is  brought  to  a 
point  where  the  structure  is  weakened. 

Smelter  coke  is  either  of  the  above  running,  say,  over  1.20% 
in  sulphur.  While  this  higher  sulphur  renders  it  undesirable 
for  smelting  or  melting  iron,  it  does  not  harm  it  for  the  smelting 
of  most  other  non-ferrous  ores. 

Stock  coke  is  that  stocked  on  the  oven  yard  instead  of  being 
loaded  direct  into  cars.  If  care  is  used  in  selecting,  when  loading, 
it  is  as  good  as  if  freshly  drawn,  with  the  exception  that  it  is 
somewhat  broken  up  by  the  double  handling,  and  is  discolored. 
Soft  coke,  heating  coke,  or  jamb  coke  is  the  cullings  from 
the  above  classes,  and  is  made  up  of  the  backs,  fronts,  and  that 
around  the  oven  doors;  this  is  often  incorrectly  called  stock  coke. 
Crushed  coke  is  crushed  and  graded  according  to  size  into  the 
following  classes:  egg,  large  stove,  small  stove,  chestnut,  %-inch 
pea,  ^2-inch  pea,  dust  coke,  coke  dust,  or  coke  breeze.  The 
first  four  grades  are  used  for  house  heating,  small  forgings,  etc., 
the  pea  size  for  chemical  works,  etc.,  and  the  dust  for  covering  the 
bottoms  of  soaking  pits  and  crucible  furnaces  to  protect  the 
brick-work  from  melted  scale. 

The  coke  obtained  as  a  by-product  from  the  distillation  of 
coal  for  illuminating  gas  is  called  gas  coke  or  gas-house  coke. 
It  is  very  hard,  and  is  largely  used  for  electric  light  carbons 
and  the  electrodes  of  electric  furnaces,  for  which  purposes  it 
is  ground,  mixed  with  a  little  tar,  molded  and  heated.  Retarded 
coke  is  coke  which  has  been  mixed  with  milk  of  lime  or  other  inert 
substance  to  reduce  the  rate  of  combustion. 

The  Diehl-Faber  process  consists  in  introducing  limestone  into 
a  charge  of  raw  coal  containing  sulphur.  It  was  claimed  that 
calcium  sulphide  was  formed  during  coking,  and  that  the  phys- 
ical properties  of  the  product,  termed  neutral  coke,  were  much 
improved. 

Coke  Bars. — See  page  411. 

Coke  Bottom. — See  Lining. 

Coke  Breeze ;  Dust. — See  above. 

Coke  Extractor. — See  page  96. 

Coke  Finery. — See  page  383. 

Coke  Furnace. — See  pages  39  and  181. 

Coke  Hole. — See  page  114. 

Coke  Malleable. — See  page  346. 

Coke  Ovens. — See  page  95. 

Coke  Pig. — See  page  343. 

Coke  Plate. — See  page  433. 

Coke  Pusher. — See  page  96. 

Coke  Refinery. — See  page  383. 

Coke  Sheet. — See  page  433. 

Coke  Tin;  Tin  Plate.— See  page  433. 

Coking  Coal.— See  Coal. 

Colander  Funnel. — See  page  60. 

Colby  Furnace. — See  page  154. 

Cold  Bend  Test.— See  page  476. 

Cold  Bending.— See  Cold  Working. 
7 


98  COLD  BLAST— COLD  WORKING 

Cold  Blast.— See  Blast. 

Cold  Blast  Charcoal  Iron. — See  page  343. 

Cold  Blast  Cupola.— See  page  182. 

Cold  Blast  Furnace. — See  page  39. 

Cold  Blast  Iron. — Pig  iron  smelted  with  a  cold  blast. 

Cold  Blowing  Iron,  Metal,  Pig. — See  page  20. 

Cold  Bottom. — See  page  376. 

Cold  Cracks. — See  page  223. 

Cold  Crystallization. — See  page  179. 

Cold  Cupping;  Dishing.— See  Cold  Working. 

Cold  Distortion.— See  Cold  Working. 

Cold  Drawing. — (i)  General:  see  page  101;  (2)  of  tubes:  see 
page  492j  (3)  of  wire:  see  page  507. 

Cold  Ductility. — See  page  331. 

Cold  Etching.— See  page  286. 

Cold  Flanging.— See  Cold  Working. 

Cold  Galvanizing. — See  page  371. 

Cold  Hammering. — See  Cold  Working. 

Cold  Hanging.— See  page  35. 

Cold  Iron;  Metal;  Pig. — (i)  In  foundry  work,  cast  iron  which  is 
thick  and  sluggish  and  does  not  pour  readily  on  account  of  being 
at  too  low  a  temperature;  (2)  cast  iron  at  a  low  temperature  in 
the  blast  furnace  and  hence  usually  higher  in  sulphur  than  normal; 
see  page  343 ;  (3)  in  Bessemer  practice  iron  which  is  low  in  silicon : 
see  page  20. 

Cold  Junction. — See  page  209. 

Cold  Lap.— See  Seam. 

Cold  Pot. — See  page  432. 

Cold  Pressing.— See  Cold  Working. 

Cold  Punching.— See  Cold  Working. 

Cold  Rolls. — See  page  431. 

Cold  Rolling. — See  pages  101  and  431. 

Cold  Saw. — A  circular  power  saw  for  cutting  metals  while  cold. 

Cold  Scaffold.— See  page  35. 

Cold  Set.— Of  metal:  chilling. 

Cold  Shearing.— See  Cold  Working. 

Cold  Short;  Shortness.— See  Brittleness. 

Cold  Short  Ore. — See  page  243. 

Cold  Shut. — (i)  The  freezing  over  of  the  top  surface  of  an  ingot 
before  the  mold  has  been  filled,  due  to  an  interruption  of  the 
stream  of  metal;  this  is  most  likely  to  happen  in  the  crucible 
process  (see  page  115),  or  where  very  small  ingots  are  made;  (2) 
the  name  for  certain  defects:  see  pages  426  and  502;  (3)  a  special 
link  for  repairing  broken  chains  which  is  closed  up  cold;  it  must 
not  be  confused  with  (i)  or  (2). 

Cold  Stable  State.— See  page  327. 

Cold  Straining.— See  Cold  Working. 

Cold  Twisting.— See  Cold  Working. 

Cold  Wild. — Wildness  due  to  the  temperature  of  the  steel  having 
been  too  low  for  the  purifying  reactions  to  take  place;  perhaps 
on  account  of  infusibility  of  the  metal  due  to  oxides. 

Cold  Working.— Straining  metal  cold  (cold  straining)  beyond  its 


COLD  WORKING  99 

elastic  limit  with  a  corresponding  effect  upon  the  physical 
properties;  this  is  the  same  as  plastic  deformation  (see  Metallog- 
raphy, p.  281)  and  overstrain  (see  Physical  Properties,  p.  334). 
Depending  upon  its  nature,  and  upon  the  further  use  or  treatment 
of  the  material,  it  may  be  beneficial  or  harmful.  The  effect  is 
due  to  the  permanent  deformation  of  the  crystals  or  grains  from 
their  normal  shape  which,  on  account  of  the  rigidity  of  the  mate- 
rial when  cold,  they  can  completely  regain  only  by  annealing 
(see  Heat  Treatment,  p.  231),  which  restores  the  original  proper- 
ties if  the  cold  working  has  not  been  excessive.  If  the  cold 
working  has  been  unequal,  this  leads  to  severe  internal  strains 
which  may  develop  so-called  season  cracks  (occurring  sometimes 
years  afterward),  or  may  cause  cracking  on  annealing,  owing  to 
the  different  rates  of  recrystallization  in  the  portions  differently 
strained.  If  the  cold  working  has  been  excessive  (overwork), 
spontaneous  cracking  may  result;  in  the  case  of  bars  this  may 
take  the  form  of  splitting  or  flaking,  and  in  the  case  of  sheets 
exfoliation  may  result,  thin  layers  peeling  off  or  crumbling  away. 
Rosenhain  states  that  as  a  general  rule  cold  working  may  be  con- 
tinued without  permanent  damage  as  long  as  the  tensile  strength 
continues  to  rise.  "When  this  strain  hardness  is  merely  to 
afford  stiffness  and  does  not  involve  the  general  question  of 
resistance  to  serious  and  continued  stresses,  it  is  perfectly  log- 
ical and  rational.  In  some  cases,  particularly  wire,  the  artificially 
induced  strength  appears  more  or  less  permanently  reliable, 
although  with  wire  ropes  subjected  to  repeated  bending,  fatigue 
failures  occur,  as  against  alternating  stresses  strain  hardness  is 
of  no  avail.  This  is  more  serious  with  rods  of  hard-drawn  or 
cold-drawn  alloys  employed  for  bolts  or  where  called  on  to  carry 
important  loads.  Practical  experience  in  such  cases  confirms 
conclusions  drawn  from  research  data  that  the  extra  strength 
from  strain  hardness  cannot  be  safely  relied  upon  for  continued 
resistance,  particularly  where  stresses  are  alternating  or  intermit- 
tent. The  best  recent  practice  shows  a  strong  and  highly  rational 
tendency  to  avoid  the  use  of  any  material  which  has  been  severely 
cold-worked,  unless  subsequently  annealed  to  remove  strain 
hardening  more  or  less  completely"  (Rosenhain).  As  opposed 
to  this  statement  of  Rosenhain's  may  be  cited  the  use  of  hard- 
drawn  wire  for  cables,  etc.,  and  the  data  in  the  following  table 
offers  evidence  that  a  careful  distinction  must  be  made  between 
cold -drawn  and  cold -rolled  material  when  subjected  to  repeated 
transverse  stresses  (see  next  page). 

Heyn  states  that  since  cold  rolling  and  cold  hammering  are  apt  to 
produce  tension  strains  in  the  core,  whereas  cold  drawing,  on  the 
contrary,  causes  tension  strains  in  the  superficial  layers,  it  is 
possible  to  reduce  strains  by  alternating  these  processes.  This 
difference  would  also  serve  to  account  for  the  results  in  the  table. 
As  regards  electrical  and  magnetic  properties,  cold  working 
decreases  the  magnetic  permeability  and  the  remanence  and  in- 
creases the  coercive  force  and  the  resistance.  The  solubility  in 
acids  is  increased  but  the  specific  heat  does  not  appear  to  be 
affected. 


100 


COLD  WORKING 


33 

^j-g 

.2 

888 

CO    Tt*  ON 

1 

SB 

,S.d 

^ 

od*  co^cT 

j 

£.3 

rcoS 

.S 

000 

1 

1  1 

5>  ° 

. 

o  o  o 

qsoq^ 

-d 

» 

"S 

rt£ 

en 

^^ 

1 

f 

1 

S 

00  vo  TJ- 

O 

en 

rt 

g 

< 

CS     M 
M 

0 

a> 

S 

1 

,0 

M 

1 
"8 

§ 

H  r^  M 
co  Tj-  10 

0 
00 

| 

w 

i 

M 

co  O   <N 

H 

(A 

cu 

(S3 

Tf    •^•'TJ- 

o 

c 

D 

•S 

^* 

^-   (N 

M 

S 

t_< 

^^ 

CM 

<D 

'1? 

,3 

^. 

000   t- 

vO 

s 

H 

rt      w 

a 

•  IH 

aT 

1 

CN    100 

M 

" 

M 

(H 

CU 

O  "S 

M-< 

-§i 

f 

§ 

»0  10  t^ 

M 

8 

*«3 

^2 

"2  ° 

il 

O 

J8 

en 

1 

,    co  O    O\ 

CM 

en 

.2 
v 

«! 

en 
H 

^ 

to 

ex 

bfl   £ 

en 

J>. 

.      .      . 

. 

MH 

g  — 

*-t—  < 

^^ 

(H     tO    OJ 

CM 

o 

•-5  ^ 

0 

^^ 

sO    O 

en 

0) 

1 

\.    M 

G 
0 

2 

d 

§ 

H    ^-  M 

1 

•8 

I 

oj 

COOO    0 

§1 

0 

S 

«    IO  0) 

"R  = 

•O 

•  d* 

s| 

S 

'    en 

id 

dT  G 

<S     . 

G 

o  ^ 

iJjS 

S 

§   co 

•  S    e/T 

fll 

it 

5 

.S  J^ 

Deflectio 
Fiber  sti 

111 

'^3  '^     M 

1 

•TJ 

3 

O   t» 

CM 

COLD  WORKING  IOI 

Cold  working  usually  consists  in  (a)  slightly  reducing  the 
cross-sectional  area  by  rolling,  hammering  or  drawing;  (b) 
distorting  the  material  by  bending,  flanging,  cupping  or  twisting; 
and  (c)  punching  or  shearing. 

Cold  rolling,  cold  hammering,  and  cold  drawing  are  employed 
for  one  or  more  of  the  following  reasons:  (a)  the  effect  upon  the 
physical  properties;  (b)  where  extreme  accuracy  as  to  size  is 
required;  (c)  to  obtain  a  very  smooth,  even  surface;  (d)  in  the  case 
of  cold  drawing,  to  produce  certain  thin,  complicated  sections, 
such  as  cornice  molding,  which  could  hardly  be  obtained  commer- 
cially by  any  other  method.  The  hole  in  a  die  through  which 
material  is  drawn  is  frequently  called  the  reduction  ring.  The 
material  (usually  round,  square  or  hexagon  bars)  is  first  pickled  to 
remove  all  the  scale.  Round  bars  for  shafting,  etc.,  are  made 
perfectly  straight  after  rolling  by  passing  them  through  a  revolv- 
ing straightening  machine  called  a  flyer.  A  curious  action  takes 
place  in  this  machine:  open  hearth  steel  bars,  over  about  0.15  % 
carbon  are  increased  slightly  in  diameter  (swelling),  while  those 
of  Bessemer  steel,  not  over  0.10%  carbon  are  reduced  slightly 
(shrinking).  The  reduction  is  very  slight  on  account  of  the 
resistance  of  the  material  to  being  worked,  and  the  very  much 
higher  cost  in  comparison  with  hot  working;  an  exception  to 
this  is  wire  drawing  (see  Wire). 

In  drawing  large  rounds,  say  over  3"  in  diameter,  breakage 
sometimes  occurs  from  too  heavy  reduction  without  proper 
annealing.  With  such  large 'sizes,  the  outside  is  worked  more 
than  the  interior,  producing  a  skin  or  shell  around  an  inner  core. 
Sometimes  only  this  shell  is  broken,  called  skin  breakage  or 
shelling. 

By  cold  working  the  tensile  strength  may  be  increased  about 
20  to  40%,  and  the  elastic  limit  60  to  over  100%. 

Cold  twisting  is  applied  to  certain  bars,  to  be  used  in  reinforced 
concrete  construction,  to  increase  their  elastic  limit  (about  the 
same  as  by  cold  rolling)  and  also  to  afford  better  bonding  with  the 
concrete.  Cold  bending  and  cold  pressing  (cupping,  dishing  and 
flanging)  are  resorted  to  more  to  obtain  some  desired  form; 
also  to  obtain  greater  stiffness,  but  rather  from  this  form  than 
from  any  effect  on  the  metal  due  to  the  cold  working  involved. 
An  application  of  cold  working  made  use  of  by  bell  hangers  to 
increase  the  elastic  limit  of  the  wire  is  known  as  frigo -tension. 
It  consists  in  subjecting  the  metal  to  repeated  tensile  stresses 
somewhat  above  the  elastic  limit. 

Cold  shearing  and  cold  punching  affect  the  metal  to  a  slight 
depth  (about  }>{Q  to  %"  or  even  more)  from  the  sheared  or 
punched  surface,  the  effect  being  proportional  to  the  thickness  of 
the  piece  and  to  its  percentage  of  carbon  or  other  hardening 
elements.  This  is  liable  to  cause  cracking  if  the  piece  is  bent 
across  a  sheared  edge  or  where  there  is  a  punched  hole,  the  danger 
being  much  greater  if  the  upper  surface  (the  entering  side  for 
the  punch  or  the  shear  blade)  is  on  the  outside  of  the  bend, 
probably  due  to  the  fin  on  the  lower  side,  and  also  to  the  fact  that 
at  the  upper  side  the  affected  metal  is  in  compression.  This 


102  COLE-  COMMON  LINES 

effect  may  be  removed  by  aaoealing  or  by  machining  off   the 

•  embrittled  portion.     First  punching  a  small  hole  and  then  ream- 
ing it  out  to  the  desired  size  is  known  as  sub-punching. 

Machining  is  "essentially  the  action  of  an  edged  cutting  tool 
and  consists  in  bringing  to  bear  upon  a  very  small  area  of  metal 
a  stress  sufficiently  intense  to  produce  rupture.  Obviously, 
however,  although  actual  rupture  is  confined  to  a  single  line  or 
surface,  severe  strain  will  be  produced  in  the  immediate  vicinity, 
so  that  in  an  ordinary  machined  or  filed  surface  the  visible  grooves 
are  accompanied  by  corresponding  sub-surface  regions  of  strained 
material.  This  region  will  be  deeper,  the  deeper  the  "cut" 
which  has  been  taken  and  the  greater  the  force  which  has  been 
employed,  and  also  the  blunter  the  tool,  i.e.,  the  larger  the  area 
to  which  the  intense  pressure  of  the  tool  has  been  applied." 
With  a  grinding  wheel  or  with  emery  paper  the  cutting  is  ex- 
ceedingly sharp  and  the  depth  is  very  slight  (Rosenhain). 

Cole  (obs.).— Coal. 

Collar. — See  page  404. 

Collaring. — See  page  415. 

Collins  (W.  W.)  Process.—  See  page  380. 

Collodion  Coating. — See  page  365. 

Colloid. — See  Solution. 

Colloidal  Metal. — See  page  128. 

Colony. — See  page  123. 

Color  Carbon. — See  Carbon. 

Color  Identity;  Names;  Scale. — Of  temperatures:  see  page  210. 

Column. — See  page  468. 

Columnar  Crystals. — See  page  125. 

Columnar  Fracture. — See  page  1 78. 

Columnar  Granulation,  Structure. — See  page  125. 

Comb. — See  page  291. 

Combination  Induction  Furnace. — See  page  153. 

Combination  Pot. — See  page  432. 

Combination  Steel. — See  page  443. 

Combination,  Water  of. — See  Water. 

Combined  Arc  and  Resistance  Furnaces. — See  page  153. 

Combined  Carbon. — See  Carbon. 

Combined  Carbon  Dioxide. — See  page  107. 

Combined  Water.— See  Water.  . 

Combining  Weight. — See  page  87. 

Combustible  Matter.— See  Fuel. 

Combustion. — See  page  202. 

Combustion  Carbon. — See  Carbon. 

Comby.— See  Pit. 

Come  to  Nature. — See  page  376. 

Commercial  Annealing. — See  page  231. 

Commercial  Elastic  Limit. — See  page  470. 

Commercial  Ore. — See  page  243. 

Comminute. — To  bring  to  an  extremely  fine  state  of  division. 

Common  Calorie. — See  page  199. 

Common  Iron. — See  page  379. 

Common  Lines, — Of  deformation:  see  page  283. 


COMPACT    GRAINED- CONGEALED    SOLUTION    103 

Compact  Grained  Pig  Iron. — Pig  iron  whose  fracture  shows  fine 

grains  or  crystals. 
Comparator. — See  page  483. 
Complete  Combustion. — See  page  202. 
Complete  Corrosion. — See  page  106. 
Complete  Crystal.— See  page  122. 

Complete  Fusion,  Zone  of. — In  blast  furnace  practice :  see  page  36. 
Complete  Heterogeneous  Equilibrium. — See  page  327. 
Compo. — See  page  64. 
Component. — See  page  326. 
Composite  Casting. — See  page  64.    - 
Composite  Fracture. — See  page  179. 
Composition  Face. — See  page  1 24. 
Composition  Formula. — See  page  86. 
Compound. — Chemical  compound:  see  page  83. 
Compound  Armor  Plate. — See  page  8. 
Compound  Casting. — See  page  64. 
Compound  Cell. — See  page  121. 
Compound  Couple. — See  page  209. 
Compound  Crystal. — See  page  124. 
Compound  Cupola. — See  page  182. 
Compound  Gas. — See  page  33. 
Compound  Ingot. — See  page  64. 
Compound  Microscope. — See  page  285. 
Compound  Radical. — See  page  87. 
Compound  Steel. — (i)  Steel  made  by  casting  layers  of  hard  and  soft 

material  together:   see  page   64;  (2)  alloy  steel:  see  page  443; 

(3)  a  name  rarely  given  to  steel  made  by  the  duplex  process:  see 

page  317. 

Compound  Stress. — See  page  332. 
Compound  Twin. — See  page  124. 
Compression. — See  page  336. 
Compression  Figure. — See  page  126. 
Compression  Test. — See  page  476. 

Compression  Hardened  (Tempered)  Steel. — See  page  229. 
Compression  Theory. — Of  hardening:  see  page  280. 
Compression  by  Wire  Drawing. — See  page  64. 
Compressive  Resilience. — See  page  331. 

Compressive  Strain;  Strength;  Stress. — See  pages  330  and  332. 
Compressometer. — See  page  476. 
Concentrated  Load. — See  page  468. 
Concentration. — Percentage  composition:  see  page  83. 
Concentric  Converter. — See  page  17. 
Concentric  Load. — See  page  332. 
Conchoidal  Fracture. — See  page  178. 
Conduction. — See  page  200. 
Conductometer. — See  page  483. 
Cone,  Fusible. — See  page  209. 
Cone  Test. — For  hardness:  see  page  478. 
Cone  Washer.— See  Ore. 
Configuration. — See  page  126. 
Congealed  Solution. — See  page  270. 


104    CONGENITAL   MALLEABLENESS— CONVECTION 

Congenital  Malleableness. — Malleable  as  produced. 

Congenital  Twin. — See  page  1 24. 

Conglomerate  Structure. — See  page  125. 

Congreayes'  Composite  Steel. — See  pag'e  64. 

Congredient  (Tiemann). — Suggested  as  a  general  term  to  include 

elements,  impurities,  or  constituents  of  a  substance. 
Congruent  Freezing. — See  page  267. 
Conley-Lancaster  Process. — See  page  140. 
Conley  Process.— (i)  Direct:  see  page  140;  (2)  electric:  see  page 

155- 

Conoid. — See  page  290. 

Consolute  (rare). — Miscible  in  all  proportions. 
Constant  Angles. — Law  of:  see  page  120. 
Constant  Heat  Sums. — Law  of:  see  page  201. 
Constant  Pressure  Thermometer. — See  page  205. 
Constant  Proportions. — Law  of :  see  page  84. 
Constant  Sum  Theory.— Of  passivity:  see  page  364. 
Constant  Volume  Thermometer. — See  page  205. 
Constantan. — See  page  209. 
Constituent. — See  pages  264  and  326. 
Constituents  of  Iron  Alloys. — See  page  272. 
Constitution  of  Special  Steels. — See  page  444. 
Constitutional  Diagram. — See  page  271. 
Constitutional  Formula. — See  page  86. 
Constitutive  Freedom,  Degree  of.— See  page  327. 
Contact,  Angle  of. — See  page  407. 

Contact  Confusion  of  Orientation.— See  pages  127  and  282. 
Contact  Heating  Furnace. — See  page  181. 
Contact  Twin. — See  page  124. 
Contact  Welding.— See  page  503. 
Continuous  Acting  Press. — See  Press. 
Continuous  Beam. — See  page  468. 
Continuous  Coil. — See  Coil. 
Continuous  Combustion. — See  page  202. 
Continuous  Curve. — See  Curve. 
Continuous  Furnace. — See  page  184. 
Continuous  Galvanizing  Process. — See  page  509. 
Continuous  Heating  Furnace. — See  page  184. 
Continuous  High  Bloomary. — See  page  144. 
Continuous  Mill. — See  page  412. 
Continuous  Producer. — See  Producer. 
Continuous  Stuckofen. — See  page  142. 
Contracting  Chill. — See  page  300. 
Contraction. — See  page  204. 
Contraction  of  Area. — See  page  336. 
Contraction  Cavity.— See  page  53. 
Contraction  Crack. — See  Crack. 
Contraction  Pyrometer. — See  page  209. 
Contraction  Pyroscope,  Wedgwood's. — See  page  209. 
Contraction  Rule. — See  page  296. 
Contraction  of  Section. — See  page  336. 
Convection. — See  page  200. 


CONVERSION— COPPER  STEEL  105 

Conversion. — See  page  81. 

Conversion  Process. — Where  a  desired  change  in  the  properties 
are  effected  by  purification,  as  of  cast  iron  into  steel. 

Converted  Bar. — See  page  71. 

Converted  Gray  Castings. — A  grade  between  gray  and  malleable 
castings,  obtained  by  heating  white  cast  iron  to  about  1010°  C. 
(1850°  F.)  for  a  few  hours. 

Converted  Steel. — Blister  steel:  see  page  71. 

Converter. — See  page  15. 

Converter  Steel  (rare). — Bessemer  steel. 

Converting  Furnace. — Cementing  furnace:  see  page  70. 

Converting  Pot. — See  page  70. 

Converting  Process. — (i)  Bessemer  process;  (2)  cementation 
process. 

Convex  Pass. — See  page  405. 

Cooling. — (i)  General:  see  page  227;  (2)  law  of:  see  page  200. 

Cooling  Bed. — See  page  414. 

Cooling  Crack.— See  Crack. 

Cooling  Curve. — See  pages  129  and  267. 

Cooling  Curve  Method. — Of  determining  critical  points:  see  page 
265. 

Cooling  Plate. — See  page  27. 

Cooling  of  Solid  Solutions. — See  page  270. 

Cooling  Table. — See  page  414. 

Cooper  Process. — See  page  140. 

Coordinate.— See  Curve. 

Cope. — See  page.  297. 

Copper.— Cu;  at.  wt.,  63.6;  melt,  pt.,  1050°  C.  (1922°  F.);  sp.  gr., 
electrolytic,  8.945,  hammered,  8.95.  It  is  found  both  free  and 
combined.  It  is  a  reddish-colored  metal,  very  malleable  and 
ductile,  possessed  of  great  tenacity,  and  is  one  of  the  best  conduc- 
tors for  both  heat  and  electricity.  Its  occurrence  in  steel  usually 
results  only  from  its  presence  in  the  ores  (see  also  page  371).  Up 
to  at  least  0.5%  it  does  not  seem  to  have  any  bad  effect  upon 
steel,  but  with  i  %,  in  conjunction  with  high  sulphur,  it  may 
cause  some  red  shortness;  it  tends  to  hinder  welding. 
In  amounts  up  to  0.5%  (commonly  o.io  to  0.30%)  it  has  re- 
cently come  into  extensive  use  in  the  manufacture  of  steel, 
particularly  thin  sheets  and  ordinary  plates  owing  to  its  effect 
in  greatly  reducing  corrosion  (q.v.,  page  366).  In  these  amounts 
and  even  up  to  1.00%  (unless  perhaps  when  accompanied  by 
abnormally  high  sulphur)  its  effect  on  the  physical  properties 
appears  to  be  a  slight  increase  in  the  elastic  limit  and  the  tensile 
strength  with,  if  anything,  a  little  better  ductility;  with  heavy 
plates  it  somewhat  resembles  nickel  in  preventing  as  good  a 
surface  as  usual.  For  influence  on  corrosion:  see  page  366. 

Copper-clad  Steel. — See  page  372. 

Copper  Coating. — (i)  For  protection  against  corrosion:  same  as 
plating:  see  page  371;  (2)  in  wire  drawing:  see  page  508. 

Copper  Plating. — See  page  371. 
Copper  Pyrites. — See  page  245. 
Copper  Steel. — See  pages  372  and  453. 


106   '  [",       COPPERAS— CORROSION 

Copperas.— See  page  245. 

Coppered  Steel.— See  page  508. 

Coppered  Wire. — See  page  508. 

Copperizing  (rare).— Coating  with  copper. 

Core. — (i)  In  case  hardening:  see  page  67;  (2)  in  molding:  see 
page  299. 

Core  Bar;  Barrel;  Binder ;  Box.— See  page  299. 

Core  Cemented ;  Cementation.— See  page  67. 

Core  Gum ;  Nail ;  Plate;  Print.— See  page  299. 

Core  Steel.— See  Edge  Steel. 

Cored  Structure. — See  page  125. 

Corey  Reforging  Process.— See  page  8. 

Coring. — See  page  299. 

Corroding  Agents.— See  page  107. 

Corrosion. — (See  also  Protection,  page  365).  The  slow  oxida- 
tion and  wasting  away  of  metal,  usually  at  ordinary  tempera- 
tures; it  may  also  be  extended  in  meaning  to  cover  the  more 
rapid  action  at  high  temperatures,  generally  called  oxidation  or 
scaling,  also  loss  resulting  from  other  chemical  reactions  either 
at  ordinary  or  high  temperatures.  (Contrast  with  erosion,  the 
loss  occurring  in  gun  barrels  when  a  film  on  the  surface  is  melted  by 
the  temperature  generated  in  the  explosion  of  the  powder  and 
blown  out  by  the  force  of  the  gases  generated;  and  abrasion, 
the  mechanical  removal  of  particles  by  the  rubbing  action  of 
another  substance.)  Its  commonest  manifestation  is  rust 
which  is  the  oxide  of  iron  formed  on  the  surface  of  corroded  iron. 
Dr.  Rideal  has  defined  corrosion  as  follows:  " Corrosion  may  be 
said  to  result  from  an  irreversible  chemical  change  proceeding 
with  a  small  velocity  and  taking  place  on  the  common  surfaces 
between  two  or  more  phases,  the  products  of  which  change  are 
continually  removed  from  the  sphere  of  action." 

Different  types  of  corrosion  may  be  classified  as  follows: 
(Some  of  the  following  definitions  were  devised  particularly  for 
non-ferrous  alloys,  but  also  apply  to  steel  alloys).  Complete 
corrosion  (Corrosion  Comm.,  Inst.  Met.,  1916)  in  which  both 
constituents  of  the  alloy  dissolve  at  approximately  the  same  rate 
and  uniformly  over  the  surface  of  the  metal.  Selective  corrosion 
(Cor.  Comm.)  in  which  only  one  constituent  dissolves.  In  the 
case  of  a  brass  it  is  usually  the  zinc  that  dissolves  selectively,  a 
process  termed  dezincification.  Distinction  should  also  be 
made  between  general  selective  corrosion,  which  occurs  over  the 
whole  surface  uniformly,  and  localized  selective  corrosion, 
which  occurs  in  spots,  also  called  pitting  or  tubercular  corrosion ; 
of  this  last  type  is  also  the  case  where  pipes  or  other  objects  of 
cast  iron  are  long  subjected  to  corrosive  action,  such  as  guns  sunk 
for  a  century  in  sea  water,  termed  graphitic  corrosion,  graphiti- 
zation,  sponge-like  decay  or  iron  cancer,  the  surfaces  being  ap- 
parently sound  but  are  readily  penetrated  by  a  sharp-pointed 
instrument  and  in  place  of  the  original  metallic  substance  is 
found  a  mass  of  oxide  of  iron  mixed  with  flakes  of  graphite. 
Corrosion  occurs  when  iron  is  exposed  to  moist  air  or  to  water 


CORROSION  107 

containing  acids  or  certain  substances  (corroding  agents).  The 
ratio  of  the  corrosion  produced  by  a  given  set  of  conditions  to  that 
of  pure  water  is  termed  the  corrosion  factor.  In  order  to  agitate 
a  solution  as  well  as  introduce  oxygen  in  making  corrosion  tests  a 
jet  of  air  is  sometimes  employed.  The  Corrosion  Committee  of 
the  Institute  of  Metals  recognizes  two  kinds  of  aeration :  gentle 
aeration  in  which  the  mechanical  agitation  of  the  water  or  solu- 
tion by  the  stream  of  air  is  reduced  to  a  minimum;  and  violent 
aeration,  in  which  the  air  impinges  directly  upon  the  surface  of 
the  metal,  or  in  any  other  way  produces  considerable  agitation 
of  the  liquid  which  is  in  immediate  contact  with  the  metal. 

According  to  the  carbonic  acid  theory  this  gas  must  be  present. 
It  is  pointed  out  by  Gibbs  that  sea  water  from  which  all  carbon 
dioxide  has  been  removed  is  alkaline  because  it  contains  an  excess 
of  basic  over  acid  substances.  In  contact  with  air  this  alkaline 
solution  will  absorb  carbon  dioxide  until  its  alkalinity  is  neutral- 
ized. The  solution  will  then  be  neutral.  At  this  stage  all  car- 
bonic acid  in  sea  water  will  be  present  in  chemical  equilibrium 
with  the  dissolved  salts.  This  is  the  combined  carbon  dioxide. 
It  might  be  called  chemically  dissolved  carbon  dioxide.  The 
atmosphere  contains  free  carbon  dioxide,  consequently  it  would 
continue  to  dissolve  in  this  neutralized  sea  water  until  equilibrium 
is  established  between  the  sea  water  and  the  atmosphere.  This 
small  additional  quantity  of  carbon  dioxide  is  physically  dissolved 
in  the  sea  water  and  is  known  as  the  free  carbon  dioxide. 

The  acid  theory  of  corrosion  "depends  on  the  simultaneous 
presence  of  oxygen,  moisture,  and  an  acid,  and  mere  traces  of 
acidity  are  sufficient  to  start  the  reaction.  As  generally  under- 
stood, the  primary  attack  is  due  to  carbonic  acid,  a  ferrous  salt 
resulting,  which  in  turn  is  acted  upon  by  oxygen  and  water  with 
the  formation  of  rust  and  the  liberation  of  the  acid.  In  this 
manner  the  process  is  continuous,  and  a  comparatively  small 
amount  of  acid  may  exercise  a  vast  influence"  (Longmuir). 

Since,  as  previously  stated,  corrosion  is  a  slow  process,  various 
methods  of  testing  have  been  suggested  to  expedite  matters  and 
thereby  obviate  tedious  delays  by  intensifying  conditions.  Such 
accelerated  tests  are  frequently  of  value  as  indicating  the  prob- 
able results  to  be  secured  from  different  substances,  but  as  it  is  not 
possible  to  intensify  all  the  conditions  in  the  same  degree,  some 
must  be  vitally  changed  in  their  relation  to  the  others  and  hence 
too  much  reliance  must  not  be  placed  upon  the  net  results  with- 
out first  making  a  careful  comparison  with  those  secured  under 
the  actual  conditions  of  service  which  it  is  sought  to  determine. 
An  accelerated  test  sometimes  employed  in  this  country  was 
devised  by  the  Committee  on  Corrosion  of  the  American  Society 
for  Testing  Materials.  A  piece  of  the  metal  to  be  tested  ma- 
chined to  2"  X  Y^"  X  He"  is  suspended  by  a  small  hole  near 
one  end  on  a  glass  rod  or  other  inactive  and  non-conducting  sub- 
stance for  2  hours  in  an  aqueous  solution  of  20%  (by  weight) 
of  sulphuric  acid  at  ordinary  temperatures.  The  percentage  of 
loss  in  weight  is  used  as  the  index. 

In  general,  the  addition  of  small  amounts  of  an  inorganic  salt 


io8  CORROSION 

in  water  increases  the  corrosive  action  of  the  solution  until  a' 
maximum  effect  is  reached,  termed  the  critical  concentration. 
Further  addition  decreases  the.  "corrosive  action  of  the  solution 
and  at  the  saturation  point  (limiting  concentration)  corrosion  is 
inhibited.  Certain  experiments  have  shown  that  concentrated 
solutions  of  most  salts  are  less  corrosive  than  pure  water,  some  pf 
the  exceptions,  within  different  temperature  ranges,  being 
ammonium  chloride,  sodium  sulphate,  potassium  nitrate,  and 
barium  chloride.  The  corrodibility  usually  increases  with  in- 
crease of  temperature.  Changes  in  action  may  take  place  at  a 
definite  temperature  (inversion  temperature) :  Thus  above  14°  C. 
(57°  F.)  solutions  of  sodium  chloride  have  greater  corrosive  effect 
on  iron  than  distilled  water;  below  this  temperature  the  reverse 
is  the  case  "(Friend). 

According  to  the  electrolytic  theory,  when  iron  (or  a  given 
substance)  is  in  contact  with  a  more  electro-positive  substance, 
or,  due  to  heterogeneousness  of  composition,  when  certain  particles 
or  constituents  are  more  electro-negative  than  others,  in  the  pres- 
ence of  moisture  Or  of  water  containing  dissolved  substances  and 
acting  as  an  electrolyte,  a  current  is  set  up  which  causes  oxidation 
or  solution  of  the  iron  or  of  the  more  electro-negative  constituent. 
According  to  Longmuir  it  "depends  upon  the  solubility  of  iron  in 

Eure  water,  or,  expressed  in  another  form,  upon  the  pressure  of 
ree  hydrogen  ions  in  the  purest  water."  This  action  may  also 
be  increased  or  diminished  by  the  flow  of  a  current  of  electric- 
ity generated  outside  of  the  couple,  depending  upon  its  direction. 
The  Bureau  of  Standards  has  used  the  terms  electrolytic  corro- 
sion when  the  damage  is  caused  by  stray  electric  currents, 
and  self -corrosion  for  the  natural  corrosion  (also  termed  autoelec- 
trolysis  or  autogenous  electrolysis)  when  structures  in  the 
ground  decay  unaccelerated  by  an  external  e.m.f .  In  this  theory 
it  is  stated  that  it  takes  place  at  ordinary  temperatures  only  in 
the  presence  of  water  through  the  reaction  Fe  -f-  2  H'— >Fe"  +  2  H. 
This  means  that  a  metallic  iron  atom,  electrically  neutral,  inter- 
acts with  two  hydrogen  ions  present  in  water  and  which  carry  elec- 
trical charges;  the  result  is  the  production  of  an  iron  atom  which 
takes  up  the  two  electric  charges  from  the  hydrogen  ions,  and  the 
deposition  of  two  atoms  of  hydrogen.  "All  have  agreed  up  to 
the  present  in  regarding  carbides  as  being  electro-negative  (that 
is,  having  positive  electro  -affinity  or  a  greater  tendency  to  exist 
in  the  molecular  than  in  the  ionic  form).  Hence  this  action 
should  be  cathodic,  and  they  should  not  be  attacked  by  corrosive 
liquids.  That  this  is  so  may  be  seen  by  microscopical  exami- 
nation" (Aitchison).  Coefficient  of  corrosion  is  sometimes  used  in 
connection  with  the  corrosion  of  an  anode,  and  is  the  ratio  of 
actual  corrosion  observed  to  that  which  would  have  occurred  if  all 
of  the  electrode  reactions  determined  by  Faraday's  law  had  been 
concerned  solely  in  corroding  the  anode;  this  has  also  been 
termed  efficiency  of  corrosion.  The  experiments  of  J.  N.  Friend 
and  of  Heyn  have  shown  that,  although  absence  of  electrolytic 
cells  in  a  very  pure  steel  does  retard  the  commencement  of  corro- 


CORROSION— CORRUGATED  SHEET  109 

sion,  it  does  not  affect  the  rate  of  corrosion  once  the  process  has 
begun  (Rosenhain). 

Certain  substances  produce  marked  reactions  at  high  tempera- 
tures at  which  they  may  even  be  melted.  An  example  is  the 
method  of  etching  with  calcium  chloride  introduced  by  Saniter 
(See  Metallog.,  page  287).  Iron  is  slightly  soluble  in  molten  zinc. 
In  the  case  of  galvanizing  pans  it  appears  advantageous  to  keep 
the  silicon  and  phosphorus  low,  while  the  content  of  manganese 
or  carbon  does  not  seem  to  have  much  effect.  The  temperature 
of  the  bath  is  of  much  greater  importance,  the  effect  increasing 
gradually  up  to  about  490°  C.  (915°  F.),  and  above  this  very 
rapidly  being  about  30  times  greater  at  530°  C.  (985°  F.)  than 
below  490°  C. 

The  relative  corrodibility  of  cast  iron  and  steel  depends  on 
given  conditions.  Thus,  in  ordinary  air  cast  iron  is  usually  more 
resistant,  also  when  completely  submerged  in  water;  but  in 
sulphuric  acid  the  reverse  is  true. 

Certain  conclusions  drawn  by  Aitchison  (/.  I.  &  S.,  1916-1- 
90-91)  are  as  follows: 

(1)  That  corrosion  of  steel  takes  place  purely  by  the  action  of 
ferrite  on  the  solid  solution. 

(2)  The  action  upon  pure  ferrite  may  be  due  entirely  to  the 
potential  difference  set  up  in  consequence  of  the  different  solu- 
tion pressures  of  the  grains  of  metal,  and  the  inter-granular  ce- 
ment, it  being  probable  that  the  latter  is  possessed  of  greater  e.m.f. 

(3)  The  percentage  of  a  third  element  added  to  iron  and  carbon 
must  be  sufficiently  great  to  produce  a  fairly  high  percentage  in 
the  solid  solution,  if  there  is  to  be  any  beneficial  effect. 

(4)  The  electromotive  force  of  the  solid  solution  with  respect 
to  the  corrosive  liquid  is  the  deciding  factor. 

(5)  Pearlite  as  a  whole  does  not  corrode  as  a  whole,  but  as  a 
mixture  of  ferrite  and  cementite,  the  disappearance  of  the  latter 
being  due  to  mechanical,  and  not  to  chemical,  action. 

(6)  Carbides  are  not  decomposed  by  ordinary  corrosive  agents, 
and  act  merely  as  the  cathode  to  the  anode  of  ferrite  or  solid 
solution.     Stead  says   (ibid.,  p.  99):  "On  long  etching  polished 
sections  of  any  aggregate  of  iron  crystals  in  dilute  nitric  acid, 
cupric  ammonium  chloride,  etc.,  the  crystals  with  cube  faces 
parallel  to  the  surface  are  always  the  slowest  to  be  attacked  and 
stand  out  in  bold  relief  above  the  surfaces  of  the  other  crystals 
of  different  orientation.     Further  sections  of  the  same  crystal  of 
iron  cut  parallel  to  and  at  an  angle  to  the  cube  face  if  immersed 
in  acid  and  connected  by  wires  to  a  galvanometer  give  an  electric 
current,  proving  that  the  cube  face  is  electro-negative  to  the 
other  face.     The   assumption   of  Aitchison   that   the   solution 
pressure  of  iron  crystals  varies  with  the  orientation  is  therefore 
fully  justified,  and  it  is  proved  that  strains  produced  by  forcing 
a  needle  into  a  cube  face  are  not  the  cause  leading  to  the  develop- 
ment of  square  etching  pits." 

Corrosion  Factor. — See  page  107. 
Corrosion  Test. — See  page  107. 
Corrugated  Sheet. — See  page  433. 


1 1  o  CORSIC AN  PROCESS— CRITH 

Corsican  Process. — See  page  140. 

Cort  Mill. — See  page  409. 

Cort  Process.— See  page  374. 

Coruscation. — The  emission  of  sparks  or  flashes. 

Cotton  Tie  Mill. — See  page  415. 

Counter-current  Principle. — See  page  204. 

Country  Heat. — See  page  71. 

Couple. — See  page  208. 

Coupling  Box. — See  page  407. 

Coupon. — (i)  In  shearing  plates,  a  piece  of  suitable  size  and  shape 
for  physical  tests  not  quite  detached  from  the  piece  it  is  to  repre- 
sent; (2)  in  forgings,  an  extension  left  to  be  cut  off  and  turned 
down  for  testing. 

Course. — Of  bricks,  a  layer  or  row. 

Cover. — (i)  The  lid  of  a  crucible;  (2)  in  the  puddling  process,  man- 
ganese is  said  to  cover  the  carbon  in  the  bath  when  the  former  is 
high  enough  to  prevent  the  latter  from  being  oxidized  for  some 
time. 

Cowper-Coles  Process. — (i)  For  electrolytic  iron:  see  page  166; 
(2)  sherardizing:  see  page  371. 

Cowper  (E.  A.)  Process. — See  page  380. 

Crab. — See  page  407. 

Crack. — A  fissure  which  has  opened  up  to  'a  certain  extent  due  to 
strains  or  brittle  material.  Those  produced  by  rolling  and  forg- 
ing are  known  respectively  as  rolling  cracks  and  forging  cracks. 
Where  cracks  are  formed  on  the  outside,  due  to  the  rapid  heating 
of  cold  material,  they  are  called  heating  cracks  or  expansion  cracks. 
Cooling  cracks  or  contraction  cracks  are  due  to  the  outside  not 
being  able  to  contract  uniformly  during  cooling;  in  castings  this 
is  termed  checking.  Thermal  cracks,  hot  cracks  or  heat  cracks 
are  those  produced  by  repeated,  alternate,  sudden  heating  and 
cooling  of  the  surface  as  in  the  case  of  the  rolls  for  rolling  hot 
steel  which  are  subjected  to  the  hot  metal  followed  immediately 
by  cooling  from  the  water  spray;  this  also  occurs  at  times  with 
railroad  wheels  and  brake  shoes,  due  to  their  mutual  action — 
often  referred  to  as  wheel  burns  and  brake  burns  respectively. 
An  internal  crack  or  fissure  is  one  which  has  formed  in  the  inte- 
rior, but  does  not  (usually)  extend  through  to  the  outside;  this  is 
due  to  excessive  longitudinal  strains,  either  from  cold  working  or 
from  too  rapid  cooling  from  the  outside.  In  shearing  hot  billets, 
etc.,  particularly  those  high  in  carbon,  fine  cracks  may  be  formed 
at  the  ends  where  the  water  drops  on  them;  they  are  called  water 
cracks. 

Cradle. — See  page  431. 

Crafts  Furnace. — See  page  155. 

Cremer  Process. — See  page  30. 

Cramp  Bar. — See  page  415. 

Creeping. — (i)  In  rolling:  see  page  408;  (2)  in  testing;  see  page  4  72. 

Cricoid. — See  page  290. 

Crimped  Sheet. — A  sheet,  one  corner  or  a  portion  of  which  has 
been  doubled  or  bent  upon  itself  during  rolling. 

Crith.— See  Hydrogen.j 


CRITICAL  CONCENTRATION— CRUCIBLE  <       1 1 1 

Critical  Concentration. — See  page  108. 

Critical  Cooling  Velocity. — See  page  447. 

Critical  Deformation. — And  grain  growth:  see  page  216. 

Critical  Interval. — See  page  265. 

Critical  Mechanical  Tempera ture. — See  page  331. 

Critical  Points. — (i)  General:  see  page  264;  (2)  determination  of: 
see  page  265. 

Critical  Range. — Of  temperature:  see  page  265. 

Critical  Strain. — See  page  216. 

Critical  Temperature. — See  page  264. 

Crocodile. — See  page  489. 

Crocodile  Hammer. — See  page  196. 

Crocodile  Shears.— See  Shears. 

Crocodile  Skin. — See  page  229. 

Crocodile  Squeezer. — See  page  377. 

Crook. — A  distortion  in  castings  produced  in  cooling. 

Crookes'  Radiometer. — See  page  207. 

Crop ;  Crop  End. — See  Discard. 

Cropping  Shears. — See  Shears. 

Cross  Breaking  Rupture. — See  page  336. 

Cross  Breaking  Strength. — Of  cast  iron:  see  page  484. 

Cross  Pane. — See  Pane. 

Cross  Piling. — See  page  378. 

Cross  Rolls ;  Rolling. — (i)  of  plates,  etc. :  see  page  414;  (2)  of  tubes : 
see  page  490. 

Cross-section ;  Cross-sectional  Area. — See  page  468. 

Cross  Welding. — See  page  502. 

Crossed  Twinning. — See  page  1 24. 

Crova's  Pyrometer. — See  page  208. 

Crown. — Of  plates:  see  page  414. 

Crown  Bar. — Merchant  bar  of  wrought  iron. 

Crucia  Steel. — See  page  451. 

Crucible. — The  hearth  of  a  blast  furnace:  see  page  27. 

Crucible. — Also  called  pot,  is  used  for  melting  small  amounts  of 
various  materials,  but  more  particularly  for  the  manufacture 
of  crucible  steel.  For  this  industry  crucibles  are  made  of  a 
high  quality  of  clay  mixed  with  a  little  powdered  coke  (clay 
crucible  or  white  pot),  or  of  a  mixture  of  clay  and  graphite 
(graphite,  plumbago,  or  blacklead  crucible). 

Graphite  crucibles  can  be  made  to  contain  a  heavier  charge, 
and  also  a  greater  number  of  heats.  They  are  made  of  a  mix- 
ture of  Ceylon  graphite,  German  clay  and  pure  sand,  the  final 
composition  being  approximately: 

Carbon 50% 

Silica 35 

Alumina 1 1 

Iron  oxide,  etc 4 

The  clay  is  dried,  ground,  made  into  a  paste  with  water,  and 
the  sand  and  graphite  thoroughly  mixed  in,  after  which  the 
mass  is  allowed  to  remain  for  a  few  days  in  a  damp  place  to 


112  CRUCIBLE 

season  or  temper,  i.e.,  be  in  a  better  condition  for  working. 
The  amount  of  crucible  material  prepared  at  one  time  is  called 
a  batch.  A  lump  of  the  proper  size  is  cut  off,  kneaded  slightly 
to  insure  its  uniformity,  and  put  inside  a  mold  which  is  placed 
on  a  potter's  wheel,  and  the  mass  spun  up  (by  revolving  the 
wheel)  to  fill  the  mold.  The  proper  thickness  of  the  wall  is 
obtained  by  means  of  an  arm  or  profile  iron  which  descends 
and  shapes  the  inside  of  the  crucible.  The  excess  at  the  top 
of  the  mold  is  sliced  off  and  the  mold  removed.  Spinning  up 
gives  better  results  than  simple  pressing  because  it  causes  the 
flakes  or  plates  (in  which  natural  graphite  occurs)  to  take  a 
tangential  direction  and  intermesh,  thereby  binding  the  material 
together.  Artificial  graphite  is  rarely  if  ever  used  as  it  does  not 
occur  in  these  plates. 

The  crucibles  are  now  dried,  first  for  about  24  hours,  at  about 
20°  to  25°  C.  (70°  to  80°  F.),  after  which  they  are  smoothed 
up;  and  then  for  about  three  weeks  at  a  temperature  high  enough 
to  drive  off  the  hygroscopic  moisture.  They  are  then  heated 
(annealed  or  burned)  in  an  oven  (annealing  oven)  for  about  three 
days  at  a  temperature  of  about  815°  C.  (1500°  F.)  to  drive  off 
all  the  combined  water.  The  crucibles  are  stacked  up  in  a 
number  of  tiers,  and,  as  they  are  still  very;  tender,  they  are  placed 
in  loose-fitting  clay  molds  (seggars  or  saggars)  which  keep  them 
from  being  crushed,  and  also  prevent  excessive  oxidation.  When 
crucibles  of  different  sizes  are  being  made  they  are  usually  nested, 
i.e.,  the  smaller  are  placed  inside  the  larger.  The  slight  oxida- 
tion of  carbon  on  the  surface,  which  always  occurs,  gives  the 
crucibles,  originally  black,  a  brownish  color  (the  color  of  the 
clay).  The  covers  are  made  and  treated  in  a  similar  manner. 

Clay  crucibles,  used  chiefly  in  England,  are  manufactured 
from  a  high  grade  of  fireclay  (Burton,  Stourbridge,  etc.),  usually 
mixed  with  about  5  %  of  good  ground  coke.  The  mixing  is 
done  very  carefully,  frequently  by  treading  the  mass  with  the 
bare  feet  on  the  treading  floor.  A  lump  is  then  placed  in  a 
flask  or  mold,  and  a  plunger  having  the  shape  of  the  interior 
is  forced  down,  being  centered  by  a  pin  passing  through  a  hole 
in  the  bottom.  The  flask  is  removed  and  the  top  of  the  crucible 
forced  inward,  by  means  of  another  conical  mold,  to  give  it 
a  shape  like  a  barrel.  After  drying  for  a  few  days  in  the  pot 
house  (where  they  are  made),  the  crucibles  are  further  dried 
at  a  somewhat  higher  temperature  near  the  flues  of  the  melting 
furnaces.  The  hole  left  in  the  bottom  is  closed  when  the  crucible 
is  set  in  the  furnace  for  use  by  throwing  in  a  little  sand  which 
frits  the  crucible  to  the  clay  stand  on  which  it  rests. 

Crucibles  are  generally  supposed  to  improve  with  age,  and 
for  this  reason  they  are  frequently  kept  for  some  time  to  season. 
If  they  have  not  been  dried  thoroughly  before  use,  the  moisture 
is  likely  to  cause  portions  to  crack  off,  called  scalping,  when  they 
are  heated.  In  some  cases  fine  cracks  (alligator  cracks,  because 
they  give  the  outside  the  appearance  of  alligator  skin)  may  de- 
velop after  a  crucible  has  been  in  service  some  time;  they  are  prob- 
ably due  to  hot  gases  and  improper  annealing.  Another  defect  of 


CRUCIBLE    CAST    STEEL— CRUCIBLE    PROCESS    113 

infrequent  occurrence  is  where  small  fissures  (pin  holes)  are  formed, 
allowing  drops  of  metal  to  run  out.  Generally  they  do  not  appear 
until  the  crucible  has  been  used  for  a  few  heats,  and  are  originated 
in  the  drying  or  the  annealing.  A  crucible  is  said  to  run  when  it 
cracks  and  the  contents  leak  out. 

Crucible  Cast  Steel.— Crucible  Steel. 

Crucible  Furnace. — See  pages  114  and  183. 

Crucible  Fusion. — See  below. 

Crucible  Process. — Also  called  pot  melting  a  process  for  the  pro- 
duction of  steel,  consisting  in  melting  down  in  closed  crucibles 
various  grades  of  iron  or  steel  with  or  without  the  addition  of 
carbon,  ore,  or  other  materials,  the  resultant  product  being  cast  in' 
a  fluid  condition.  As  ordinarily  practised,  it  is  essentially  a 
melting  operation,  there  being  little  if  any  purification,  except 
perhaps  as  regards  oxides  or  gases.  The  process  was  invented 
by  Robert  Huntsman  about  1 740.  The  most  important  modifi- 
cations are  (Howe) : 

1.  Huntsman's,  the  original  method  (sometimes  called  crucible 
fusion),  in  which  small  pieces  of  blister  or  other  highly  carburized 
steel  are  melted  alone  or  with  a  slag-making  flux  (e.g.,  glass). 

2.  Josiah  Marshall  Heath's  modification  of  adding  manganese, 
either  previously  reduced  by  heating  its  oxide  with  carbonaceous 
matter  or  reduced  in  the  process  itself  by  the  action  of  charcoal 
on  oxide  of  manganese.     Huntsman's  method  thus  modified,  it 
is  said,  is  now  the  prevalent  one  in  Sheffield. 

3.  The  carburizing  fusion   (or  cementing  fusion)   method, 
in  which  the  percentage  of  carbon  in  the  product  is  regulated 
by  the  addition  of  carbonaceous  matter  (practically  charcoal), 
is  said  to  have  been  used  in  the  last  century  by  Chalut  and  Clouet, 
and  is  the  prevalent  method  in  this  country. 

4.  Uchatius,  or  the  pig  and  ore  method,  of  melting  granu- 
lated cast  iron  with  iron  ore. 

5.  The  pig  and  scrap  method  of  melting  wrought  iron  or  steel, 
or  both,  raising  the  proportion  of  carbon  by  adding  cast  iron. 

In  all  the  above  methods  the  molten  metal  is  tranquilized 
by  killing,  i.e.,  holding  it  molten  so  as  to  yield  sound  ingots. 

6.  The  Mitis  method,  in  which  the  charge  originally  con- 
stituted in  any  of  the  above  ways,  is  tranquilized  by  the  adition 
of  ferro-aluminum  (or  aluminum)  immediately  after  fusion,  and 
is  teemed  a  few  minutes  later. 

7.  The  basic  method,  or  fusion  in  basic  instead  of  silicious 
crucibles,  to  permit  of  the  elimination  of  phosphorus  and  sul- 
phur, does  not  appear  to  have  had  any  practical  application. 

In  Bajault  and  Roche's  process  powdered  ore  and  pig  iron 
wereN  put  in  cast-iron  molds  and  heated  in  a  furnace.  The  pig 
iron  and  the  mold  reacted  with  the  ore,  the  whole  forming  one 
ingot  which  was  to  be  broken  up  and  used  in  the  crucible  process. 
The  materials  would  have  to  be  pure,  and  the  advantage  to  be 
gained  from  conducting  the  pig  and  ore  process  in  two  separate 
operations  is  not  evident.  Kern's  process  appears  to  be  a 
modification  of  the  carburizing  fusion  method,  being  conducted 
in  two  stages:  (a)  soft  open  hearth  steel  was  melted  with  charcoal 
'8 


114  CRUCIBLE  PROCESS 

in  graphite  crucibles,  (6)  the  highly  carburized  product  thus 
obtained  was  then  used  in  place  of  cement  steel,  mixed  with 
wrought  iron,  etc. 

Graphite  crucibles  (see  Crucible)  are  used  in  this  country 
and  principally  on  the  Continent;  clay  crucibles  chiefly  in 
England;  in  this  latter  case  the  process  is  sometimes  referred  to 
as  the  white  crucible  process.  The  crucible  furnace  may  be 
heated  by  gas,  coal,  or  coke.  If  the  former,  it  is  regenerative  in 
principle,  and  consists  of  a  number  of  chambers  or  holes  (melting 
holes) — about  6  to  15  holes  to  each  furnace,  each  hole  holding 
6  crucibles — in  which  the  combustion  of  the  gas  takes  place. 
The  bottoms  of  the  holes  are  covered  with  coke  dust  to  protect 
the  brick-work  in  case  a  crucible  is  broken,  and  provided  with 
a  hole  to  permit  of  cleaning.  The  covers  for  the  holes  are  some- 
times called  clamps  or  bungs.  In  coal  or  coke  furnaces  (pot  hole, 
coke  hole,  fire  hole — rarely  called  shaft  furnaces)  the  crucible 
is  set  directly  in  the  fuel,  which  is  supported  by  grate  bars,  a 
chamber  being  provided  underneath  for  cleaning,  called  the 
cave.  Poking  the  fuel  around  the  crucible  is  sometimes  called 
pottering  down  (Eng.).  Principally  on  the  Continent  and  in  a 
few  cases  in  this  country  what  is  termed  a  Krupp  Furnace  is  em- 
ployed; this  resembles  a  small  open  hearth  furnace  and  the  pots 
are  charged  and  drawn  horizontally  through  the  doors.  In 
contradistinction  to  this  the  other  type  of  furnace,  in  which  the 
pots  are  charged  and  drawn  vertically,  is  referred  to  as  a  hole 
furnace.  In  this  country  the  charge  is  ordinarily  100  pounds, 
and  the  graphite  crucible  weighs  about  50  pounds  when  new. 
The  material  employed  is  usually  wrought  iron  or  soft-steel  scrap, 
together  with  a  certain  proportion  of  charcoal  and  oxide  of  man- 
ganese; occasionally  blister  steel  is  used,  in  which  case  the  char- 
coal is  omitted.  The  larger  pieces  are  put  at  the  bottom  by  the 
pot  packer,  the  charcoal  and  oxide  of  manganese  on  these,  and 
the  smaller  pieces  at  the  top;  the  cover  is  put  on  and  the  crucible 
set  in  the  furnace  by  a  man  called  the  setter  in.  The  charge  is 
occasionally  introduced  into  the  crucible  (while  in  the  furnace) 
by  means  of  a  runnel  or  charger.  Depending  on  the  composition 
of  the  charge  (low  carbon  heats  take  much  longer  than  high 
carbon)  the  melting,  which  is  the  first  stage  of  the  process,  takes 
about  2  to  4  hours,  and  when  it  is  judged  that  this  has  taken 
place,  the  man  in  charge,  or  melter,  looks  over  the  heat,  i.e., 
uncovers  certain  of  the  pots  to  determine  with  his  eye  the  condi- 
tion of  the  contents;  if  necessary,  he  stirs  them  with  a  small 
rod  to  detect  unmelted  pieces.  When  this  period  is  completed, 
the  charge  is  allowed  to  remain  a  further  period  until  the  steel 
becomes  tranquil,  i.e.,  does  not  evolve  gas.  This  result  is  prob- 
ably effected  by  silicon,  reduced  by  carbon  acting  on  the  wall 
of  the  crucible,  combining  with  the  gases.  This  tranquilizing 
period  is  known  as  killing,  and  the  steel  when  perfectly  quiet  is 
said  to  be  dead.  The  bubbles  of  gas  which  form  and  break 
slowly  toward  the  end  of  the  killing  period  are  sometimes  called 
cat's  eyes ;  they  are  larger  than  when  the  charge  is  first  melted. 
Killing  takes  from  about  %  to  i  %  hours — usually  from  %  to  i 


CRUCIBLE  PROCESS  115 

hour— -and  if  unduly  prolonged  the  metal  when  cast  is  hard 
and  brittle  (also  called  dead),  probably  on  account  of  excessive 
absorption  of  silicon.  The  total  time  required  for  a  heat  is 
about  3  to  4  hours,  three  heats  being  made  each  turn  of  12 
hours.  When  ready  the  crucibles  are  drawn  from  the  melting 
hole  by  the  puller  out,  set  on  the  floor  and  the  covers  removed. 
In  some  cases  they  may  be  set  temporarily  in  an  iron-lined 
hole  (teeming  hole)  in  the  floor.  The  slag  (scum  or  flux)  float- 
ing on  top  of  the  steel  is  removed  (swabbed  up)  by  means  of  a 
light  iron  rod  with  a  ball  of  slag  on  one  end  (mop)  against  which 
it  chills.  Drawing  by  some  mechanical  device,  instead  of  by 
hand,  has  not  proved  satisfactory  as  the  crucibles  are  liable  to 
slip  or  else  be  crushed.  The  steel  is  now  teemed  (poured)  into 
molds,  and  any  slag  remaining  is  kept  back  by  holding  a  bar 
(flux  stick)  against  it.  Each  mold  receives  the  contents  of  one 
crucible,  or,  if  of  larger  size,  several  cruciblefuls  are  used,  care 
being  taken  in  every  case  that  the  stream  does  not  strike  the  sides, 
and  also  that  it  is  not  momentarily  interrupted,  the  latter  causing 
the  metal  to  freeze  over  (cold  shut).  Several  cruciblefuls  may 
also  be  poured  into  a  ladle  and  the  molds  filled  from  this.  The 
ingot  after  cooling  is  topped  (the  top  broken  off)  to  determine  the 
grade  by  the  appearance  of  the  fracture  (chemical  analysis  is  now 
largely  employed  for  this),  and  also  for  the  purpose  of  removing 
the  piped  portion.  Graphite  crucibles  were  formerly  allowed 
to  cool  between  heats,  but  now  are  usually  charged  hot,  i.e., 
returned  to  the  furnace  immediately  without  cooling  after  being 
inspected  for  cracks.  After  about  nine  heats  they  are  allowed  to 
cool  completely  for  more  careful  inspection,  their  average  life 
being  six  to  nine  heats.  In  English  practice,  where  clay  crucibles 
are  used,  the  life  of  a  crucible  is  about  three  heats,  and  the  charges 
are  reduced  successively  on  account  of  the  slag  line  or  flux  line 
which  is  left  after  each  operation.  The  first  charge  is  about  56 
pounds,  the  succeeding  ones  being  about  44  and  38  pounds  respec- 
tively. Owing  to  the  fact  that  the  crucible  is  cold  for  the  first 
heat,  this  takes  about  4^  to  6  hours,  the  subsequent  heat  taking 
less,  as  then  the  crucible  is  returned  to  the  furnace  immediately; 
three  heats  are  obtained  in  12  hours.  When  solid  fuel  is  used, 
care  must  be  taken  that  none  falls  into  the  crucible,  as  the  steel 
is  thereby  rendered  red  short,  and  its  fracture,  which  is  brilliant, 
is  said  to  stare.  The  store  room  in  which  the  raw  materials  for 
the  charge,  particularly  the  ingredients  for  special  steels,  is 
sometimes  called  the  medicine  room. 

"In  hammering  crucible  ingots  for  tool  steel  it  used  to  be 
customary  to  heat  them  first  to  a  comparatively  low  temperature, 
not  high  enough  to  produce  scale,  and  then  cog  (forge)  them  under 
a  steam  hammer  by  very  light  blows,  not  sufficient  to  reduce 
materially  the  dimensions  of  the  ingot  but  merely  to  smooth 
and  slightly  "  compact' '  its  surface.  The  ingot  was  then  replaced 
in  the  heating  furnace,  brought  to  as  high  a  temperature  as  its 
composition  would  permit,  being  rolled  from  time  to  time  in  a 
welding  mixture,  and  then  quickly  returned  to  the  hammer  where 
it  was  roughly  brought  to  the  required  cogged  bar  size.  The 


1 1 6  CRUCIBLE  PROCESS 

first  operation  was  known  as  saddening,  and  the  low,  non-scaling 
temperature  was  spoken  of  as  a  saddening  heat.  The  idea  was  to 
smooth  the  rough  surface  of  the  ingot  as  such  a  surface  was  less 
likely  to  be  burned  at  the  subsequent  temperature.  It  was  also 
believed  that  blowholes  lying  close  to  the  surface  would  thus  be 
closed  before  a  scaling  heat  had  a  chance  to  open  and  expose 
them  to  oxidation"  (G.  Aertsen).  "In  crucible  steel  works 
practice  it  is  sometimes  the  custom  to  heat  the  steel  to,  and  forge 
from,  what  is  called  the  wash-welding  temperature  (sufficiently 
high  to  cause  the  scale  to  run  and  also  to  promote  welding),  and 
it  is  assumed  that  if  the  material  initially  contains  cavities  or 
blowholes,  they  will  be  welded  up"  (Stead). 

General  Principles. — The  charge  contains  initially  a  moderate 
quantity  of  oxygen  as  rust,  scale,  and  the  slag  of  wrought  iron. 
This,  as  well  as  the  trifling  quantity  of  atmospheric  oxygen  orig- 
inally present,  and  free  oxygen  and  the  oxygen  of  any  carbon 
dioxide  of  aqueous  vapor  which  may  enter  by  leakage  or  by 
diffusion,  should  tend  to  form  oxide  of  iron  and  (if  the  charge 
contains  spiegeleisen  or  ferro-manganese)  of  manganese.  This 
tendency  is  opposed  by  the  carbon  of  the  crucible  walls,  which, 
especially  in  the  case  of  new  graphite  crucibles,  tends  to  take  up 
the  free  oxygen  and  to  reduce  the  carbon  dioxide  present. 

The  metallic  oxides,  melting  first  to  a  very  basic  slag,  should 
collect  at  the  bottom  of  the  crucible  and  react  on  its  walls, 
and  later,  on  the  bath  of  molten  steel.  The  first  action  of  the 
slag  on  the  metal  should  be  strongly  fining,  tending  to  oxidize 
carbon,  silicon,  and  manganese.  As  the  slag  level  is  gradually 
raised  by  the  accumulation  of  the  molten  steel  beneath,  the  slag 
corrodes  ring  after  ring  of  the  crucible  wall,  exposing  the  graphite 
or  coke  to  the  rising  underlying  metal,  which  absorbs  carbon 
voraciously.  The  fining  action  should  thus  weaken  rapidly  as 
the  slag  grows  acid  through  absorption  of  silica  from  the  crucible, 
and  through  the  reduction  of  its  oxides,  partly  by  the  metal's 
carbon  and  silicon,  partly  (in  the  case  of  strongly  graphitic 
crucibles  chiefly)  by  the  carbon  of  the  crucible.  This  fining 
probably  soon  gives  way  to  carburization,  the  carburized  me'tal 
reducing  and  absorbing  silicon  from  the  now  acid  slag  and  from 
the  acid  crucible  wall.  The  net  result,  under  usual  conditions, 
is  that  in  graphite  crucibles  the  metal  gains  in  carbon  (usually 
by  from  o  to  0.25%)  and  in  silicon  (usually  by  from  0.05  to 
0.20%);  that  if  spiegel  or  ferro-manganese  is  charged  before 
melting,  much  of  its  manganese  is  slagged,  and  the  absorption 
of  carbon  and  silicon  is  increased;  and  that  if  oxide  of  manganese 
is  charged,  part  of  its  manganese  is  sometimes,  if  not  usually,  re- 
duced and  absorbed  by  the  metal.  The  more  highly  carbureted 
the  crucible  wall,  the  greater  will  be  the  net  absorption  of  car- 
bon, manganese,  and  silicon. 

In  clay  crucibles,  the  charge  either  loses  carbon  (say  up  to 
0.25%)  or  gains  but  slightly  (say  up  to  0.06%),  while  gaining 
but  slightly  in  silicon,  unless  manganese  or  its  oxide  be  present. 

If  the  charge  contains  charcoal  or  graphite,  this  both  carburizes 
the  metal  during  heating  to  the  melting  point  (probably  most 


CRUCIBLE  PROCESS  1 1 7 

of  its  carbon  is  absorbed  by  the  steel),  and  greatly  shortens  and 
weakens,  if  it  does  not  eliminate,  the  fining  period  by  protecting 
iron  and  manganese  from  oxidation,  and  by  reducing  at  least  a 
part  of  their  oxides. 

If,  on  the  other  hand,  oxide  of  manganese  is  charged,  it  tends 
to  intensify  and  prolong  the  fining,  to  postpone  and  enfeeble 
the  carburization,  opposing  the  action  of  the  charcoal. 

The  silicon  absorbed  during  the  killing  period  probably 
tranquilizes  the  steel,  principally  by  removing  any  oxides  or  free 
oxygen  present,  although  in  addition  it  is  supposed  to  give  the 
steel  the  property  of  retaining  gases  which  it  contains,  such  as 
nitrogen. 

Sulphur  increases  gradually  but  constantly,  being  taken  up 
perhaps  from  the  pyrites  of  the  clay  or  graphite,  perhaps  from 
that  of  the  fuel,  very  small  quantities  of  sulphur  dioxide  entering 
the  crucible. 

Phosphorus,  in  like  manner,  increases  slightly  when  clay  or 
graphite  crucibles  are  used,  but  is  eliminated  gradually  in  basic 
crucibles. 

Comparative  Quality  of  Crucible  Steel. — As  already  stated, 
in  the  United  States  it  is  generally  customary  to  use  wrought 
iron  (sometimes  basic  open  hearth  steel)  in  contact  with  charcoal 
in  the  crucible  itself.  In  Europe  blister  steel  is  usually  em- 
ployed. This  latter  method  necessitates  a  separate,  very  lengthy 
treatment  previous  to  the  melting  down  in  crucibles.  It  is 
claimed  (and  also  disputed)  that  as  good  steel  is  produced  by  the 
American  method  as  by  the  English.  Crucible  steel  is  better 
than  open  hearth  or  Bessemer  steel  for  the  following  reasons: 

(a)  The  materials  used  are  more  carefully  selected. 

(6)  Smaller  units  are  handled  which  receive  greater  attention. 

(c)  It  is  not  exposed  to  the  atmosphere. 
The  relative  qualities  are : 

1.  Crucible, 

2.  Open  hearth, 

3.  Bessemer, 

and  taken  in  the  same  order,  the  crucible  steel  has  least  contact 
with  the  atmosphere,  and  the  Bessemer  most. 

It  is  claimed  that  it  is  possible  to  produce  in  the  electric  furnace 
steel  of  crucible  quality  or  even  better.  The  electric  furnace 
with  a  basic  hearth  permits  of  refining  not  possible  in  the  acid 
crucible.  It  also  operates  without  furnace  gases  in  contact  with 
the  charge  and  can  be  made  to  exclude  nearly  all  circulation  of 
air.  Electric  steel  is  made  in  larger  units  and  for  this  reason 
cannot  receive  the  same  meticulous  care;  for  the  same  reason 
its  uniformity  should  be  greater  especially  for  large  ingots. 
However,  the  most  expensive  tool  steel  is  still  manufactured  in 
crucibles. 

A  number  of  early  processes  or  modifications  did  not  possess 
any  particular  novelty  or  value,  as  will  be  seen  from  the  follow- 
ing: Charles  Atwood's  process  consisted  essentially  in  melting 
together  wrought  iron  and  cast  iron  (spiegel  preferred).  George 


1 1 8        CRUCIBLE  STEEL— CRYPTODIMORPHISM 

Brown's  process  consisted  in  melting  wrought  iron,  cut  up  into 
small  pieces,  with  charcoal  pig  iron,  in  the  proportion  of  about 
three  parts  of  the  former  to  one  of  the  latter.  Victor  Gallet 
coated  puddle  bar  with  a  paste  consisting  of  certain  proportions 
of  limestone,  vegetable  mold  or  clay,  carbonate  of  potash,  oxide 
of  manganese,  resin,  soot,  wood  charcoal,  etc.,  and  melting  in  a 
crucible.  Charles  Low  devised  a  truly  remarkable  process  in 
which  wrought  iron  was  to  be  melted  in  crucibles  with  a  mixture 
of  manganese  dioxide,  plumbago,  charcoal,  and  niter.  A.  V. 
Newton's  process  consisted  in  heating  crucibles  and  their  charge 
of  blister  bars  in  an  auxiliary  furnace  before  putting  them  in  the 
regular  melting  furnace,  by  which  means  he  claimed  a  consider- 
able reduction  in  the  time  required.  William  Onions'  process 
consisted  in  melting  in  a  crucible  two  parts  of  hematite  ore,  four 
parts  of  steel,  and  94  parts  of  pig  iron,  the  resulting  metal  being 
poured  directly  into  molds,  and  the  castings  subsequently  an- 
nealed. D.  S.  Price  and  E.  C.  Nicholson's  process  consisted  sim- 
ply in  melting  refined  pig  with  suitable  proportions  of  wrought 
iron.  Obersteiner  fused  pig  with  wrought  iron.  Sudre's 
process  consisted  in  melting  steel  (blister  steel)  in  a  reverberatory 
furnace,  instead  of  in  a  crucible,  and  the  employment  of  bottle 
glass  for  flux.  In  J.  L.  Talbot  and  J.  D.  M.  Stirling's  process 
various  proportions  of  oxides  were  added  to  blister  bars  during 
melting  in  crucibles  to  get  steel  with  different  percentages  of 
carbon.  John  Thompson  proposed  to  produce  refined  cast  steel 
by  melting  it  in  a  furnace  (instead  of  in  crucibles)  of  peculiar 
construction,  resembling  a  puddling  furnace,  in  which  were 
placed  troughs  or  other  vessels  containing  the  metal.  Win. 
Vickers'  process  consisted  in  melting  wrought-iron  scrap  with 
ground  charcoal  and  oxide  of  manganese;  cast-iron  scrap  might 
also  be  used. 

Crucible  Steel. — Steel  made  by  the  crucible  process;  also  called 
cast  steel,  Huntsman  steel  (obs.),  pot  steel  (Eng.). 

Crude  Iron  (obs.). — Untreated  pig  iron. 

Crude  Steel.— See  page  343. 

Crumble. — Of  the  cutting  edge  of  a  tool  which  breaks  away  in 
small  particles  because  it  is  too  hard  or  has  not  the  proper  shape. 

Crushed  Coke. — See  page  97. 

Crushed  Steel. — An  abrasive  material  usually  made  by  quenching 
high-carbon  steel  from  a  high  temperature  and  crushing,  followed 
by  tempering  to  a  straw  color. 

Crushing. — Breaking  up  into  a  smaller  size,  for  such  material  as 
ore,  limestone,  etc. 

Crushing  Strength. — Compressive  strength :  see  page  330. 

Crux. — An  abbreviation  sometimes  used  for  crucible. 

Cryocarbide. — See  page  273. 

Cryohydrate. — See  page  266. 

Cryosel. — See  page  266. 

Cryptocellular  Structure. — See  page  126. 

Cryptoclastic  Structure. — See  page  126. 

Cryptocrystalline. — See  page  126. 

Cryptodimorphism. — See  page  122. 


CRYSTALS— CRYSTALLOGRAPHY  1 1 9 

Crystals. — (i)  General:  see  below;  (2)  laws  of:  see  page  120;  (3) 
properties  of:  see  page  121;  (4)  structure  of:  see  below. 

Crystal-boundary  Etching. — See  page  127. 

Crystal  Centers. — See  page  1 20. 

Crystal  Cleavage. — See  page  123. 

Crystal  Debris. — See  page  125. 

Crystal-field  Etching;  Crystal-figure  Etching. — See  page  127. 

Crystal  Grain.— See  page  122. 

Crystal  Growth. — See  page  121. 

Crystal  Plane. — See  page  123. 

Crystal  Size. — See  page  121. 

Crystal  Skeleton. — See  page  122. 

Crystal  Thrust— See  page  121. 

Crystal  Unit  Slipping. — See  page  281. 

Crystalliform. — See  below. 

Crystalline. — See  below. 

Crystalline  Aggregate. — See  page  125. 

Crystalline  Antimony. — See  Antimony. 

Crystalline  Boron. — See  Boron. 

Crystalline  Carbon. — See  Carbon. 

Crystalline  Deformation. — See  page  126. 

Crystalline  Force. — See  page  121. 

Crystalline  Fracture. — See  page  178. 

Crystalline  Grain. — See  page  122. 

Crystalline  Growth.— See  page  213. 

Crystalline  Magnesite. — See  page  397. 

Crystalline  Movement. — See  page  281. 

Crystalline  Slip.— See  page  282. 

Crystalline  Solid  Solutions. — See  page  270. 

Crystalline  State. — See  below. 

Crystalline  Structure. — See  below. 

Crystalline  Tin.— See  Tin. 

Crystallite. — See  page  122. 

Crystallization. — (i)  General:  see  below;  (2)  systems  of:  see  page 
120;  (3)  water  of:  see  page  499. 

Crystallization  by  Annealing. — See  page  213. 

Crystallographic  Amorphizing. — See  page  282.' 

Crystallographic  Axis. — See  below. 

Crystallographic  Plane. — See  below  and  page  123. 

Crystallography. — The  study  of  crystals  which  are  solid  bodies 
bounded  by  plane  surfaces  or  faces  at  definite  angles  to  each  other, 
and  formed  by  the  arrangement  of  the  molecules,  which  arrange- 
ment is  symmetrical  to  certain  imaginary  lines  or  axes  (crystallo- 
graphic  axes)  intersecting  at  the  center,  or  to  certain  planes 
(Crystallographic  planes  or  planes  of  symmetry)  intersecting 
the  Crystallographic  axes.  The  relative  inclination  of  the  axes 
to  a  certain  plane  or  line  is  called  the  orientation  of  the  crystal. 
This  regular  structure  (and  a  body  possessing  it)  is  termed  crys- 
talline or  crystalliform  (crystalline  state) ;  a  body  in  which  these 
properties  are  absent,  amorphous  or  non-crystalline.  The 
measurement  of  the  angles  of  a  crystal  is  performed  by  the  aid  of 
an  instrument  called  a  goniometer. 


1 20  CRYSTALLOGRAPHY 

Systems  of  Crystallization. — Crystals  may  be  classified  accord- 
ing to  their  form  or  crystallization,  into  six  different  systems 
which  are  (Moses  and  Parsons,  "Mineralogy,  Crystallography, 
etc.,"  6): 

i.  Isometric  (cubic,  monometric,  regular,  tesseral,  or  tessular) 
system :  Three  interchangeable  axes  at  right  angles  to  each 
other. 

1  2.  Tetragonal  (dimetric,  monodimetric,  pyramidal,  quadratic, 
or  quarternary)  system:  Three  axes  at  right  angles,  of  which 
two  are  interchangeable. 

3.  Hexagonal    (rhombohedral,    rhombohedric,    or    monotri- 
metric)  system:  Four  axes,  three  of  which  lie  in  one  plane  at  60 
degrees  to  each  other  and  are  interchangeable;  the  fourth  is  at 
right  angles  to  the  other  three. 

4.  Orthorhombic    (anisometric,    orthosymmetric,    prismatic, 
rhombic,  or  trimetric)  system :  Three  axes  at  right  angles  but  not 
interchangeable. 

5.  Monoclinic  (clinorhombic,  hemiprismatic,  monoclinohedral, 
monosymmetric,  or  oblique)  system:  Three  non-interchangeable 
axes,  two  of  which  are  oblique  to  each  other;  the  third  is  at 
right  angles  to  the  other  two. 

6.  Triclinic  (anprthic,  asymmetric,  clinorhomboidal,  doubly 
oblique,  tetarto  prismatic,  or  triclinohedral)  system:  Three  non- 
interchangeable  axes  at  oblique  angles  to  each  other. 

Any  general  reference  to  the  optical  properties  of  crystals 
(polarization,  etc.)  is  omitted  as  metallic  crystals  are  opaque 
except  in  extremely  thin  sections  which  have  no  practical 
importance. 

Moses  and  Parsons  (loc.  cit.,  2  et  seq.)  give  the  following  three 
fundamental  laws  of  crystals : 

1.  Law  of  constancy  of  facial  angles:  In  all  crystals  of  the 
same   substance   the   angles   between   corresponding  faces   are 
constant. 

2.  Law  of  symmetry:  All  crystals  of  any  one  substance  are  of 
the  same  grade  of  symmetry. 

3.  Law  of  simple  mathematical  ratio:  In  all  crystals  of  the 
same  chemical  substance,  if  the  intercepts  of  any  face  upon  the 
crystallographic  axes  are  divided,  term  by  term,  by  the  corre- 
sponding intercepts  of  any  other  face,  the  quotients  will  always  be 
simple  rational  numbers  or  infinity  or  zero. 

Formation  of  Crystals.— According  to  the  researches  of  Bragg, 
in  which  he  employed  a  Rontgen  ray  spectrometer  to  study  the 
constitution  of  crystals,  they  are  made  up  of  atoms  and  not  of 
molecules.  There  are  different  theories  or  hypotheses  as  to  their 
origin  and  growth.  According  to  one,  they  start  from  a  globular 
or  utricular  mass  (globulite).  These  are  sometimes  referred  to  as 
embryonic  crystals.  In  heterogeneous  crystal  mixtures,  ab- 
sorbens  is  the  name  which  has  been  given  to  one  crystal  form 
when  it  expands  with  decreasing  temperature  and  absorbs  the 
other  form  (Guertler).  The  points  of  origin  in  building  up 
crystals  which  may  be  invisibly  small  and  grow  by  accretion  or 
coalescence  (merging)  are  called  by  Tammann  crystal  centers. 


CRYSTALLOGRAPHY  121 

The  space-lattice  theory  of  crystallization  is  that  the  atoms 
(or  molecules)  are  not  in  actual  contact  but  separated  in  accord- 
ance with  a  well  denned  and  regular  pattern  or  structure.  The 
cubical  space  (this  refers  to  volume  and  not  to  form)  included 
within  intersecting  planes  passing  through  a  set  of  neighboring 
atoms  is  called  the  space-lattice.  Quincke's  hypothesis  holds 
that  crystallization  commences  when  in  the  liquid  state,  the 
liquid  first  separating  into  two  immiscible  phases,  one  of  which  is  in 
relatively  large  quantity  and  is  composed  of  the  pure  substance, 
the  other  or  smaller  containing  any  impurities  or  eutectic.  This 
acts  somewhat  like  an  emulsion  of  oil  and  water,  the  smaller  or 
oily  liquid  forming  the  walls  (foam  walls  or  cell  walls)  of  foam 
cells  filled  with  the  pure  substance,  each  spheroid  of  which  being 
isolated  can  develop  its  own  orientation,  either  while  still  liquid 
or  after  complete  solidification.  Such  a  structure  is  known  as  a 
foam.  Depending  upon  their  mode  of  formation  and  structure 
they  have  been  divided  into  first,  second,  and  third  order,  or 
first-class  and  second-class  cells ;  also  primary,  secondary  and 
tertiary  crystals.  Osmond  and  Werth  referred  to  simple  cells, 
bounded  by  ferrite,  and  compound  cells  which  were  larger  and 
composed  of  dendritic  crystals.  The  formation  of  grains  im- 
mediately upon  solidification  Belaiew  calls  granulation,  and  where 
it  occurs,  the  granulation  range  or  zone  ;  and  this  action,  primary 
crystallization ;  the  secondary  effect  when  pearlite  is  formed  at 
Ari,  secondary  crystallization.  Arnold  suggests  centrifugal 
extrusion  to  express  the  action  when  metal  crystallizes  and  any 
substances  are  thrown  to  the  edge.  According  to  Desch  it  is 
not  necessary  to  assume  that  crystallization  is  due  to  the  exist- 
ence of  a  separate  crystalline  force,  as  the  ordinary  cohesive 
forces  in  solids  have,  in  crystals,  vector  properties  and  act  more 
strongly  in  certain  directions  than  in  others;  this  is  implied  in 
the  idea  of  a  crystal,  and  the  phenomenon  of  crystal  thrust  is  to 
be  explained  as  the  result  of  the  vectorial  character  of  cohesion. 
The  size  of  crystals,  i.e.,  their  growth,  under  normal  conditions 
depends  upon  the  rate  of  solidification  or  cooling  while  they  are 
still  at  high  temperatures  where  conditions  permit  of  sufficient 
mobility  for  the  rearrangement  of  the  particles  so  certain  crystals 
grow  at  the  expense  of  the  others.  Howe  refers  to  parallel 
growth  where  crystals  extending  in  the  same  direction  are  con- 
nected or  grow  together. 

Properties  and  Structure  of  Crystals. — Morphology  (particu- 
larly in  biology)  is  the  science  of  form  and  structure;  morphometry 
is  the  method  of  measuring  external  forms.  Isomorphism  or 
homoeomorphism  is  where  different  substances  crystallize  in 
identical  or  closely  related  forms.  Mitscherlich's  law  states 
that  elements  in  compounds  may  be  replaced  by  other  similar 
elements  without  changing  the  crystalline  form  (e.g.,  manganese 
partly  replacing  iron  in  cementite).  Monomorphic  refers  to  a 
crystal  of  the  same  or  similar  form.  Polymorphism  or  multiple 
isomorphism  is  the  property  of  crystallizing  in  more  than  one 
form;  where  there  are  two  forms,  the  term  dimorphism  is  some- 
times used,  and  for  three  forms,  trimorphism;  isodimorphism  is 


122  CRYSTALLOGRAPHY 

where  two  substances,  in  addition  to  independent  forms,  can 
crystallize  in  another  common  form;  if  the  presence  of  both 
is  necessary  it  is  a  case  of  cryptodimorphism  or  cryptomorphism. 
Metamorphism  is  the  change  or  reformation  (recrystallization) 
due  to  some  agent  such  as  heat  (thermal  metamorphism  or 
pyrometamorphism) ;  a  rock,  for  example,  which  owes  its 
(crystalline)  form  to  heat  is  said  to  be  pyromorphous ;  pyrocrys- 
taltine  refers  to  a  body  crystallized  from  the  molten  state. 
Static  metamorphism  is  a  change  brought  about  by  gradual  or 
steady  forces;  dynamic  metamorphism,  by  suddenly  applied 
forces;  if  such  a  change  is  incomplete  it  is  a  case  of  hemimeta- 
morphosis.  A  pseudomorphic  crystal  or  pseudomorph  is  one 
which  results  (a)  from  the  substitution  or  chemical  alteration  of, 
and  has  the  same  form  as,  a  crystal  previously  existing,  or  (b) 
from  deposition  in  the  space  which  a  crystal  previously  occupied. 
An  allomorph  is  a  pseudomorph  where  there  is  no  change  in 
chemical  composition.  A  paramorph  is  a  crystalline  form  of  one 
substance  assumed  by  another  of  similar  chemical  composition 
but  of  different  properties.  Heteromorphic  indicates  a  sub- 
stance differs  in  form  or  properties  from  the  normal.  The  prefix 
holo-  is  used  to  denote  completeness,  as  holocrystalline,  entirely 
crystalline  (containing  no  amorphous  matter);  holosymmetric, 
entirely  symmetric;  holoisometric,  completely  crystalline  ac- 
cording to  the  isometric  system;  holoaxial,  having  all  the  axes 
but  none  of  the  faces;  holohedral  or  homohedral,  .having  the 
complete  set  of  crystal  faces  for  the  given  form.  An  anhedron 
or  faceless  crystal  is  a  crystal  without  definite  bounding  planes; 
a  hemihedron  is  one  having  only  half  the  regular  number  of 
faces.  A  crystal  is  said  to  be  orthobasic  when  the  axes  are  at 
right  angles  to  each  other.  Complete  crystals,  i.e.,  those  which 
have  been  formed  when  the  conditions  were  favorable  for  their 
complete  development,  are  called  idiomorphic,  automorphic  or 
euhedral  crystals;  a  large  crystal  of  this  nature  is  sometimes 
termed  a  metacryst.  If  their  bounding  surfaces  are  determined 
by  adjacent  (interfering)  crystals  or  bodies,  they  are  called 
incomplete,  hemicrystalline  or  allotriomorphic  crystals.  In  the 
case  of  metals  these  last  are  termed  crystalline  grains,  crystal 
grains  or,  more  usually,  simply  grains  or  granules,  and  a  struc- 
ture made  up  of  them  is  said  to  be  granular  or  granulitic. 

In  the  primary  crystallization  referred  to  above  the  growth  is 
by  a  process  of  repeated  branching  in  the  directions  where  there 
is  the  least  interference.  These  formations  are  termed  crystal- 
lites, star-like  crystallites,  skeletal  crystals,  skeleton  crystals, 
crystal  skeletons,  and  particularly  because  of  this  branching  form 
and  their  supposed  resemblance,  dendrites,  or  dendritic,  ar- 
borescent, tree -like,  fir-tree,  pine-tree  and  fern-leaf  crystals 
or  crystallites.  A  microlite  is  a  more  or  less  completely  defined 
microscopic  crystal.  Cuboid  is  a  term  tentatively  applied  to 
crystals  which  appear  to  be  of  cubical  form  before  this  has  been 
determined  definitely.  Crystallites  which  are  wedge  shaped  are 
sometimes  said  to  be  cuneiform  or  cuneate. 

A  unit  crystal  is  the  smallest  piece  of  matter  which  can  possess 


CRYSTALLOGRAPHY  1 23 

all  the  properties  of  a  crystal.  The  components  or  grains  of  a 
crystallite  form  are  sometimes  referred  to  collectively  as  colonies 
(of  grains).  The  term  spicule  is  used  to  describe  something 
which  is  thread-like  in  form  with  pointed  ends.  If  before  solidi- 
fication is  complete  the  still  molten  portion  is  removed,  the  crystal 
so  exposed  is  called  an  isolated  crystal.  In  the  case  of  solutions 
of  certain  organic  substances  Lehmann  found  globules  which 
acted  on  polarized  light  in  the  same  way  as  ordinary  (transparent) 
crystals  and  which  he  termed  liquid  crystals ;  the  same  term  is 
also  applied  to  cases  which  have  been  found  with  metallic  (solid) 
crystals  which  are  extremely  plastic,  resembling  fluids  in  this 
respect,  although  in  general  a  crystalline  structure  has  a  decid- 
edly embrittling  effect. 

Crystal  Planes. — These  may  be  classified  as  follows : 

1.  Planes  of  symmetry:  A  plane  which  "so  divides  the  crystal 
that  either  half  is  the  mirrored  reflection  of  the  other,  and  every 
line  perpendicular  to  the  plane  connects  corresponding  parts  of 
the  crystal  and  is  bisected  by  the  plane  of  symmetry"  (Moses 
and  Parsons,  5);  sometimes  referred  to  as  the  crystallographic 
plane. 

2.  Motion  planes    (Howe):  Those   where   movement  of  the 
particles  occurs,  also  termed  planes  of  weakness. 

(a)  Cleavage  planes :  Those  along  which  a  crystal  breaks 
or  separates,  "always  parallel  to  faces  of  forms  in  which 
the  substance  can  crystallize  .  .  .  True  cleavage  is 
obtained  with  equal  ease  at  any  part  of  a  crystal,  and 
there  is  only  a  mechanical  limit  in  the  closeness  of  one 
cleavage  to  the  next"  (Moses  and  Parsons,  146-7). 

(6)  Gliding  planes:  Those  where  "it  has  been  observed 
that  pressure  in  certain  directions  will  either  produce  a 
separation  along  a  definite  plane,  which  is  not  a  true 
cleavage  plane,  or  else  will  develop  a  twin  structure 
(secondary  twinning)  with  this  gliding  plane  as  the  twin 
plane"  (Moses  and  Parsons,  148). 

(c)  Parting  planes:  "The  planes  along  which  a  gliding  has 
occurred  may  thereafter  be  planes  of  easy  separation  or 
parting,  differing  from  true  cleavage,  however,  because 
in  parting  the  easy  separation  is  limited  to  the  planes 
of  actual  gliding,  while  true  cleavage  is  obtained  with 
equal  ease   at  all  other  parallel  planes"   (Moses  and 
Parsons,  149). 

(d )  Slip  planes :  Those  along  which  slip  occurs  (see  Metal- 
lography, page  282). 

Crystal  Cleavage. — The  separation  or  rupture  of  a  crystal 
along  cleavage  planes  (see  above)  which  represent  directions  of 
minimum  cohesion;  also  called  intra-crystalUne  or  trans-crystal- 
line rupture  (cleavage  brittleness),  i.e.,  across  or  through  the 
grains  or  crystals,  as  distinguished  from  intercrystalline  rupture 
which  occurs  between  them.  "Cleavage  is,  in  general,  limited 
to  directions  parallel  to  the  simpler  and  more  frequently  occurring 
crystal  forms.  In  the  isometric  system  it  is  parallel  to  the  cube 


1 24  CRYSTALLOGRAPHY 

(cubical),  octahedron  (octahedral)  or  dodecahedron  (dodecahe- 
dral).  In  the  tetragonal  system  it  is  basal  or  prismatic  and  only 
rarely  pyramidal.  In  the  hexagonal  system  it  is  basal,  prismatic, 
or  rhombohedral,  but  rarely  pyramidal.  In  the  other  systems 
the  arbitrary  selection  of  axes  prevents  a  simple  classification  of 
cleavages,  but  the  selection  usually  makes  one  direction  of 
cleavage  pinacoidal  and  two  of  equal  ease  prismatic  .  .  . 
Cleavage  is  said  to  be  perfect  or  eminent  when  obtained  with 
great  ease,  affording  smooth  lustrous  surfaces.  Inferior  degrees 
of  ease  of  cleavage  are  called  distinct,  indistinct,  or  imperfect, 
interrupted,  in  traces,  difficult"  (Moses  and  Parsons,  147). 
Lateral  and  diagonal  cleavages  are  those  respectively  parallel 
to  the  lateral  face  and  the  diagonal  plane.  Certain  metamorphic 
rocks  have  their  minerals  or  constituents  segregated  or  deposited 
(interpenetration)  between  the  strata  or  grains,  called  joint 
foliation  where  cleavage  has  occurred,  or  cleavage  foliation 
where  rupture  has  been  caused  by  bending  (faulting  foliation), 
and  when  deposited  as  a  layer  (stratification  foliation),  such 
surfaces  of  deformation  are  called  foldings. 

To  indicate  the  property  of  cleavage  special  terms  are  used  such 
as:  Lamination,  to  indicate  that  a  substance  is  composed  of 
sheets  which  can  be  separated  as  such;  fissile,  of  a  crystal  which 
can  be  split;  sectile,  of  a  crystal  which  can  be  sliced,  the  slices 
being  friable  or  crumble  readily.  Different  types  of  cleavage 
are  indicated  by  the  terms  heterotomous,  unusual;  orthotomous, 
at  right  angles  to  each  other;  orthotypous,  perpendicular. 

Twinning. — Twins  or  twin  crystals,  hemitropes  or  compound 
crystals,  are  formed  by  the  symmetrical  intergrowth  of  two  like 
crystals;  when  the  two  individuals  penetrate  each  other  they 
constitute  a  penetration  twin,  and  when  they  do  not,  a  contact 
twin  or  juxtaposition  twin  (Moses  and  Parson,  65).  Macle  is 
given  (I.A.T.M.)  as  a  synonym  for  twin  crystal,  but  in  mineral- 
ogy it  is  the  name  of  a  mineral  (chiastolite)  having  an  internal 
tesselated  or  cruciform  structure  (Dana).  The  twinning  plane 
(see  above)  is  symmetrical  to  the  two  portions  of  the  twin,  but 
is  not  a  plane  of  symmetry  for  either  alone.  It  may  be  consid- 
ered that  twinning  has  occurred  by  rotation  of  one  portion  180 
degrees  about  a  line  normal  to  the  twinning  plane,  termed  the 
twin  or  twinning  axis.  In  the  case  of  contact  twins  the  twinning 
plane  is  also  the  contact  plane,  called  the  composition  face,  but 
it  is  not  the  same  with  penetration  twins.  The  crystalline 
arrangement  which  produces  a  definite  kind  of  twinning  is  called 
the  twinning  law.  There  are  a  number  of  different  types  of 
twin  each  of  which  has  its  own  law.  If  there  are  only  two  indi- 
viduals, it  is  called  simple  twinning ;  if  more  than  two,  repeated 
twinning.  Multiple  or  polysynthetic  twinning  is  repeated  twin- 
ning after  the  same  law;  crossed  or  grid-iron  twinning  (cyclic  or 
stellate  twins),  repeated  twinning  after  two  laws.  If  the  indi- 
viduals are  connected  in  different  ways,  it  is  called  a  compound 
twin.  Twinning  may  occur  (a}  during  crystallization  (congenital 
twins),  (b)  as  a  result  of  straining  alone  of  crystals  already 
formed  (mechanical  twins),  or  (c)  especially  for  iron,  straining 


CRYSTALLOGRAPHY  1 2  5 

followed  by  annealing  (annealing  twins).  The  structure  on  the 
surface  produced  by  twinning  is  a  series  of  bands;  from  their 
relative  size  annealing  twins  are  also  termed  broad  twins,  while 
mechanical  twins  are  called  narrow  twins  or  Neumann  lamellae 
or  Neumann  bands.  Pseudosymmetry  is  where  the  symmetry  is 
apparently  of  a  higher  form  than  normal,  often  due  to  twinning. 
Crystalline  Structure. — The  term  structure  (texture  is  used  in 
the  same  sense  but  should  properly  be  restricted  to  woven  fabrics) 
refers  to  the  arrangement  and  appearance,  or  organization,  of  the 
different  constituents  of  a  substance.  Rosenhain  designates  as 
simple  metals  those  composed  of  only  one  kind  of  crystals.  A 
body  (and  its  structure)  is  said  to  be  massive  when  it  does  not 
show  crystalline  faces,  whether  it  is  crystalline  or  not  (Moses  and 
Parsons).  A  crystalline  aggregate  is  a  body  composed  of  coher- 
ent crystals  or  grains  which  cannot  be  broken  apart,  i.e.,  are 
not  elastic.  It  is  pseudocrystalline  when  apparently  of  a  uni- 
form crystalline  formation,  but  really  a  composite  of  small 
grains  or  pieces  densely  compacted.  A  porphyritic  structure 
consists  of  a  semi-crystalline  (partially  crystalline)  or  finely 
crystalline  or  glassy  portion,  appearing  compact  to  the  naked 
eye,  called  the  ground  mass,  matrix,  magma,  or  base,  in  which 
are  embedded  well  defined  crystals  called  phenocrysts.  In 
metallography  these  terms  refer  to  the  constituent  which  is 
predominant.  If  the  phenocrysts  are  absent,  it  is  termed 
felsitic ;  granitoid  or  granulitic,  composed  of  grains  or  crystals  of 
about  the  same  size.  An  oolitic  (egg-shaped)  structure  is  one 
made  up  of  spherical  individuals  each  of  which  has  grown  around 
a  nucleus,  usually  of  some  other  material.  A  cored  structure 
has  the  interior  or  core  of  different  structure  or  material  from  the 
exterior.  A  poikilitic  structure  is  composed  of  relatively  large 
crystals  or  grains  which  contain,  without  definite  arrangement, 
numbers  of  smaller  individuals  of  various  substances.  A  hemi- 
pelic  structure  is  one  resembling  fine  clay;  a  fragmental  structure, 
one  composed  of  pieces  of  a  preexistent  substance,  or  crystal 
debris.  A  conglomerate  is  a  structure  composed  of  rounded 
fragments;  breccia  structure  is  similar  except  the  component 
fragments  are  sharp.  Columnar  granulation,  columnar  structure, 
or  columnar  crystals,  is  where  the  grains  or  the  crystals  are  ar- 
ranged in  columns;  in  this  sense  the  term  prismatic  is  sometimes 
applied  to  alloys;  if  the  columns  are  very  long  and  slender,  as  in 
wrought  iron,  they  are  termed  filaments  or  fibers,  and  the  struc- 
ture fibrous,  fibriform,  nerve,  capillary  (hair-like),  or  bacillar 
(rod-shaped).  A  radiating  structure  is  one  consisting  of  lines 
radiating  from  a  common  center;  it  is  stellate  when  the  radiations 
are  of  equal  length.  Margarite  structure  (Vogelsang)  is  where 
crystallites  are  arranged  like  strings  of  pearls.  A  spherulitic 
structure,  peculiar  to  vitreous  rocks,  and  in  eutectics  of  alloys 
rapidly  cooled,  is  so  called  because  of  the  small  spherulitic  bodies, 
or  spherulites,  they  contain  (I.A.T.M.).  A  structure  is  some- 
times referred  to  as  mushy  when  it  has  no  distinct  grains.  Druse 
(drusy  cavity)  is  a  term  (corresponding  to  geode  in  geology) 
used  for  a  cavity  formed  during  freezing,  into  which  the  ends  of 


126  CRYSTALLOGRAPHY 

crystals  or  crystallites  project;  needle-shaped  crystals  found  in 
druses  are  also  -termed  acicular.  Certain  terms  referring  to 
minute  forms  simply  add  to  the  ordinary  term  (already  given) 
the  prefix  micro,  and  for  which  no  further  definitions  are  neces- 
sary: microcrystallography,  microcrystalline,  microcrystallitic, 
microgranular,  micrpgranulitic,  microgranitoid,  micromeritic 
(microcrystalline),  microporphyritic,  microspherulitic.  Crypto- 
crystalline  or  microcryptocrystalline,  a  structure  of  crystalline 
particles  too  small  to  be  detected  by  the  naked  eye.  Cryptoclas- 
tic,  composed  of  fine  grains  broken  apart  from  a  preexistent  form. 
When  it  is  composed  of  cells  the  following  designating  terms  are 
used:  Monocellular  or  unicellular,  one  cell  only;  polycellular  or 
multicellular,  many  cells;  homocellular,  cells  of  the  same  kind; 
heterocellular,  cells  of  different  kinds;  microcellular,  minute 
cells;  cryptocellular,  cells  so  minute  as  to  be  invisible.  A  poly- 
centric  body  or  structure  is  one  built  up  from  many  nuclei  or 
centers.  A  structure  consisting  of  intersecting  lines  having  the 
appearance  of  a  mesh  or  net  is  accordingly  termed  mesh,  net, 
network,  lattice,  reticular,  reticulated,  cancellated,  or  plaited 
structure.  If  the  meshes  are  of  identical  size  and  shape  they  may 
be  termed  isodictyal.  Howe  refers  to  network  as  an  assemblage 
of  walled  cells  (with  a  kernel  contained  within  the  envelope, 
shell,  or  cell  walls),  and  to  network  size  as  the  average  size  of  the 
walled  cells  which  make  up  the  network  (A.S.T.M.,  1911-275); 
he  considers  the  term  phenocellular  for  this  structure  as  too 
pedantic.  A  structure  presenting  the  appearance  of  overlapping 
plates  is  sometimes  called  imbricated.  A  thin  plate,  such  as 
graphite,  is  termed  a  lamella  or  lamina,  and  a  structure  composed 
of  or  containing  such  plates,  lamellar  or  laminated. 

According  to  Osmond  and  Cartaud  a  body  may  be  considered 
both  as  cellular  (having  a  network  structure)  and  amorphous; 
the  former  in  so  far  as  it  is  formed  of  polyhedral  (many-sided) 
grains,  and  the  latter  when  the  deformations  are  governed  only 
by  the  direction  of  the  strains  and  are  independent  of  the  crystal- 
line structure.  Whence  arise  three  kinds  of  deformation,  which 
they  call  crystalline,  cellular  and  banal.  Every  deformation 
has  some  sort  of  general  configuration  (deformation  figure  or  com- 
pression figure)  which  may  be  called  its  silhouette,  and  which  is 
the  boundary  of  elementary  deformations.  It  is  the  area  of  a  pre- 
viously polished  body  that  loses  its  polish  where  the  deformations 
take  place.  A  silhouette  is  naturally  continuous  and  closed. 
Its  form  on  an  ordinary  metal  with  cellular  structure  depends 
only  on  the  form  of  the  sample  and  on  the  nature  or  direction 
of  the  strains;  but  it  ceases  to  be  the  same  on  an  isolated  crystal, 
for  then  its  form  can  be  in  relation  with  the  crystalline  symmetry. 
An  observation  of  the  lines  of  deformation  on  rupture  shows  that 
under  the  influence  of  even  sudden  loads  (impact)  such  lines 
appear  in  nicked  specimens  inside  the  crystals;  these  Osmond 
calls  specific  lines  in  contradistinction  to  the  ordinary  lines 
produced  by  static  stress. 

If  a  surface  composed  of  crystal  faces  or  cleavages  is  attacked 
by  any  solvent,  the  action  proceeds  most  rapidly  along  certain 


CRYSTALLOGRAPHY  127 

planes  (solution  planes)  forming  pits  or  depressions  (etching  pits) 
of  varying  depths  whereby  characteristic  figures  (etching  figures) 
are  produced.  The  term  vesicle  (or  vesicular)  should  not  be 
applied  to  these  as  it  refers  to  small  approximately  spherical 
cavities  commonly  occurring  in  volcanic  rocks.  J.  Czochralski 
distinguishes  three  kinds  of  etching  figure  resulting  from  (i) 
crystal-boundary  etching,  (2)  crystal-field  etching,  and  (3) 
crystal-figure  etching.  Where  a  cavity  resulting  from  etching 
or  from  a  gas  bubble  has  the  form  of  a  crystal  it  is  termed  a 
negative  or  internal  crystal.  Referring  to  the  tripartite  nature  of 
metals  Howe  says  (Metallography,  268-9)  that  they  are  "(i) 
microscopically  crystalline,  in  that  each  microscopic  grain  is  a 
true  crystal;  (2)  microscopically  cellular,  in  that  they  are  aggre- 
gations of  these  grains,  each  of  which  may  be  regarded  as  a  cell, 
probably  with  an  envelope;  and  (3)  macroscopically  amorphous, 
because  the  orientation  changes  from  grain  to  grain,  and  hence 
the  mass  as  a  whole  has  no  internal  orientation  of  its  own." 
Where  crystals  with  different  orientation  are  in  contact,  Howe 
refers  to  contact  confusion  of  orientation  as  a  reason  why  rupture 
ordinarily  avoids  the  joints.  Howe  refers  (ibid.,  275)  to  "what 
may  be  called  grains  of  two  orders  in  ferrite,  each  large  grain,  or 
grain  of  the  first  order,  being  made  up  of  several  fragments, 
or  grains  of  the  second  order,  with  the  usual  grain  shape  and 
oriented  alike."  Rotation  effect  is  a  term  used  to  describe  the 
lighting  up  and  darkening  of  the  crystalline  grains  in  the  etched 
surfaces  of  polished  metals  when  rotated  before  oblique  rays 
(Heycock  and  Neville) ;  Ewing  and  Rosenhain  refer  to  this  as 
the  selective  effect  of  oblique  light  (I.A.T.M.);  more  recently 
Rosenhain  suggests  as  preferable  the  term  oriented  lustre. 
Schillerization  "refers  to  the  peculiar  bronze-like  lustre,  "Schil- 
ler," in  certain  minerals,  due  to  the  presence  of  minute  in- 
clusions in  parallel  positions"  (Mellor). 

When  the  surface  or  a  section  of  certain  alloys  is  polished  (and 
sometimes  etched)  there  can  be  seen  markings  consisting  of  paral- 
lel or  intersecting  lines  or  bands  which  have  received  different 
names  according  to  their  structure.  The  structure  produced 
by  narrow  twinning  (see  above)  has,  after  its  discoverer,  been 
called  Neumann  bands,  lamellae  or  lines.  The  Widmanstatten 
or  W  structure  or  lines  is  discussed  under  Meteorites  (page  291) ; 
Sauveur  suggests  that  it  might  be  termed  cleavage  structure. 
In  discussing  the  deformation  lines  in  manganese  steel  Howe 
says  (Metallog.,  460)  "The  lines  which  form  when  this  substance 
is  deformed  may  be  divided  into  the  surface  bands  which  form  on 
previously  polished  surfaces,  and  the  etching  bands  which  are 
developed  by  polishing  and  etching  after  deformation."  Howe 
terms  manganese  steel  lines  those  peculiar  to  this  type  of  steel 
and  differing  from  ordinary  slip  bands.  What  Howe  calles  X 
bands  "are  rough  striae  found  on  polishing  and  etching  iron  which 
has  been  severely  deformed  plastically .  .  .  Their  nature  is  not 
known"  (Metallog.,  452).  Eutectiferous  bands  or  eutectiform 
patterns  are  those  caused  by  eutectics,  usually  observed  after 
etching  in  addition  to  polishing.  Translation  banding  is  what 


128  CUBIC  SYSTEM—CURVE 

is  due  to  movement  but  is  distinguished  from  that  produced  by 
twinning.  "Thorns  and  boundary  edgings  (also  called  spikes 
and  bordered  boundaries  by  Osmond,  Fremont,  and  Cartaud) 
are  unexplained  deep-seated  markings  developed  occasionally  in 
low-carbon  steel,  but  only  by  etching  and  only  after  plastic 
deformation,  and  therefore  clearly  representing  neither  mechan- 
ical defects  nor  local  concentration  of  impurities"  (Howe, 
Metallog.,422). 

What  has  been  termed  a  metallic  fog  has  been  obtained,  e.g., 
by  adding  small  pieces  of  metallic  lead  to  fused  colorless  lead 
chloride;  dark  colored  crystals  are  formed  on  solidification  with  a 
structure  resembling  that  of  gold  ruby  glass.  A  colloidal  metal 
is  referred  to  as  one  which  is  so  finely  divided  it  will  remain 
indefinitely  in  suspension  in  water;  in  this  condition  colors  are  de- 
veloped differing  from  that  of  the  ordinary  form;  the  precious 
metals  have  been  those  principally  studied  in  this  connection. 

Cubic  System. — Of  crystallization:  see  page  120. 

Cubical  Cleavage. — See  page  124. 

Cuboid;  Cuboidal. — See  page  122. 

Cull. — A  piece  of  rejected  material. 

Culm.— See  Coal. 

Cumberland  Process. — See  page  365. 

Cumulative  Class. — In  hardening:  see  page  279. 

Cuneate;  Cuneiform. — See  page  122. 

Cunningham's  Formula. — For  tensile  strength:  see  page  338. 

Cup  and  Cone. — See  page  32. 

Cup  Fracture. — See  page  1 79. 

Cupola. — See  page  182. 

Cupola  Crucible. — See  page  182. 

Cupola  Furnace. — (i)  See  page  182 ;  (2)  a  name  formerly  given  to  a 
small  blast  furnace  built  ol  brick  and  bound  with  bands. 

Cupola  Metal. — Molten  pig  iron,  obtained  by  melting  in  a  cupola. 

Cupping. — (i)  A  defect  in  wire  which  causes  it  to  break  with  a  cup 
fracture;  (2)  pressing  a  sheet  or  plate  into  cup  form,  as  in  the 
manufacture  of  one  kind  of  seamless  tubing;  also  called  dishing: 
see  page  101. 

Cupric  Reagents. — For  etching;  those  containing  some  salt  of 
copper:  see  page  287. 

Cure. — In  rolling:  see  page  412. 

Curing  Color. — See  page  371. 

Curve. — Also  called  graph ;  a  diagram  to  illustrate  graphically  the 
relative  change  or  changes  between  two  (or  three)  conditions 
affecting  a  body,  when  one  or  more  of  these  conditions  varies; 
further,  to  obtain,  by  interpolation,  any  relation,  within  a  given 
range,  from  a  number  of  relations  actually  determined.  The 
usual  method  is  to  lay  off  a  vertical  line  near  the  left-hand 
margin  of  a  sheet  of  paper,  intersecting,  usually  at  right  angles, 
a  horizontal  line  near  the  bottom;  these  lines  are  called  the  axes, 
and  they  determine  the  location  and  the  shape  of  the  curve  by 
means  of  perpendicular  distances  from  them,  called  coordinates. 
Where  the  axes  intersect  is  the  zero  point  or  origin.  Divisions 
on  the  axes  represent  units  of  the  related  conditions.  For  ex- 


CURVE 


129 


ample,  in  the  case  of  the  effect  on  tensile  strength  produced  by 
changes  in  carbon  content,  the  vertical  axis  will  represent  pounds 
per  square  inch,  and  the  horizontal  axis,  percentages  of  carbon. 
The  tensile  strength  and  the  carbon  content  of  a  specimen  having 
been  actually  determined,  from  the  point  on  the  vertical  axis 
corresponding  to  the  tensile  strength  obtained  a  line  is  drawn  at 
right  angles  until  it  intersects  another  line  drawn  at  right  angles 
from  the  point  on  the  horizontal  axis  representing  the  known 
percentage  of  carbon,  the  intersection  giving  one  point  of  the 
curve.  A  number  of  other  points  have  been  similarly  plotted, 
they  are  connected  by  a  line,  called  a  curve,  which  may  be  straight, 
broken,  or  curved.  Any  point  on  this  curve  is  called  a  locus 
(plural,  loci),  the  perpendicular  distance  of  which  from  the 


PIG.   14. — Triaxial    diagram. 

• 

vertical  axis  is  termed  the  abscissa ;  that  from  the  horizontal 
axis,  the  ordinate.  A  sudden  change  in  the  shape  of  a  curve  is 
called  a  jog,  break,  or  perturbation,  and  the  curve  is  said  to  be 
discontinuous :  a  curve  which  is  smooth  or  regular  is  called 
continuous  or  jogless. 

Assigning  values  to  a  point  on  a  curve  is  termed  interpolation 
if  such  points  lies  within  limits  actually  determined;  extrapola- 
tion if  it  lies  outside  such  points,  the  assumption  being  that  for  a 
certain  distance  at  least  there  will  be  no  sudden  change  in  the 
nature  or  form  of  the  curve  and  the  corresponding  values.  The 
first  method  is  of  course  much  less  liable  to  error  than  the  second. 

A  cooling  curve  shows  the  rate  of  cooling  of  a  body  plotted  with 
degrees  of  temperature  and  units  of  time  as  coordinates.  The 
diagram  similarly  obtained  by  heating  is  known  as  a  heating 
curve.  A  solubility  curve  shows  the  percentage  of  a  substance 
which  is  dissolved  at  different  temperatures.  An  equilibrium 


130  CUT  BAR  IRON— CYCLIC  TWIN 

curve  (see  page  326)  shows  the  relation  between  temperature  and 
composition  of  a  heterogeneous  system,  in  which  the  phases 
present  are  in  equilibrium  with  each  other  (I.A.T.M.).  A 
freezing-point  curve,  melting-point  curve,  or  fusion  curve 
represents  the  variation  in  the  temperature  of  freezing  (or  melt- 
ing) of  a  series  of  alloys  corresponding  to  changes  in  composition. 
The  triaxial  diagram  is  designed  to  show  graphically  the 
relation  between  three  variables  whose  sum  is  a  constant  quantity 
(e.g.,  percentages).  As  shown  in  the  sketch,  the  loci  are  obtained 
by  the  intersection  of  vertical  lines  drawn  perpendicular  to  the 
three  axes  AB,  AC,  and  DE. 

Cut  Bar  Iron  (rare). — (Wrought)  iron  bars  cut  for  crucible  melting. 

Cut  Out. — Of  linings,  etc.,  corroded. 

Cutaneous  Blowholes. — See  page  55. 

Cutlery  Temper. — See  Temper. 

Cutting. — Of  slags,  flames,  or  gases,  oxidizing. 

Cutting  Blast.— See  Blast. 

Cyano -nitride  of  Titanium. — See  Salamander. 

Cyclic  Twin. — See  page  124. 


D 

Dy. — Chemical  symbol  for  dysprosium:  see  page  84. 

Daelen  Mill. — See  page  408. 

Daelen  Process. — See  page  63. 

Daelen-Pszczolka  Process. — See  page  317. 

Dalton's  Law. — See  page  85. 

Dam;  Dam  Plate;  Dam  Stone. — Of  an  old-style  blast  furnace:  see 
page  32. 

Damascus  Steel. — A  metal  formerly  made  at  Damascus,  by  some 
direct  process,  covered  with  beautiful  figurations  (damaskeening), 
principally  used  for  sword  blades  and  gun  barrels.  Very  good 
imitations  are  now  made  in  France  and  elsewhere.  These  are 
produced  by  welding  together  bars  or  strips  of  wrought  iron  and 
(wrought)  steel  in  different  ways  to  obtain  the  desired  pattern. 
After  being  given  the  final  shape,  the  surface  is  etched  with  acid 
or  other  substance,  leaving  part  bright  and  part  dark,  or  of  differ- 
ent colors.  A  cheap  imitation  consists  in  taking  a  piece  of  ordi- 
nary iron  or  steel,  and  pasting  on  it  a  sheet  of  paper  on  which  is 
printed  a  pattern.  Upon  etching,  the  portion  covered  by  the 
printing  is  not  attacked.  The  original  steel  contained  tungsten, 
nickel,  manganese,  etc. 

Damask  Steel ;  Damaskeening ;  Damasking.— See  Damascus  Steel. 

Damped  Down.— Of  a  blast  furnace:  see  page  37. 

Daniels  Mill. — See  page  420. 

Darby  Recarburizing  Process. — See  Recarburization. 

Dasymeter. — An  instrument  for  measuring  loss  of  heat  in  a  furnace 
by  analysis  of  the  waste  gases. 

Datum  Points. — See  page  473. 

Daubreelite. — See  page  292. 

Davy  Portable  Converter. — See  page  23. 

Davy  Process. — See  page  19. 

Day  Gas  Pyrometer. — See  page  207. 

De  Dion-Bouton  Process. — See  page  70. 

De  Laval  Feeding  Head ;  Ring. — See  page  60. 

De  Laval  Process. — See  page  140. 

De  Lisle's  Scale. — Of  temperatures:  see  page  205. 

De  Marre  Formula. — See  page  8. 

De  Vathaire  Process. — See  page  385. 

De  Wees  Wood  Process.— See  page  369. 

Dead. — (i)  Molten  steel  which  is  perfectly  quiet,  i.e.,  does"not 
evolve  gas:  see  page  114;  (2)  steel  which  has  been  burnt  or 
contains  high  sulphur,  so  that,  on  rolling  or  forging,  it  cracks 
or  breaks  up:  see  page  226. 

Dead  Annealing. — See  page  232. 

Deadhead. — See  page  56. 

Dead  Load.— See  page  468. 

Dead  Melt;  Melted,  Molten.— Of  materials  in  a  furnace,  etc., 
fully  or  completely  melted,  and  from  which  no  gas  is  being 
evolved;  killed. 


132    DEAD    OFF   THE    BOIL— DEPHOSPHORIZATION 

Dead  Off  the  Boil  (Eng.). — When  no  more  carbon  is  left  in  a  metal- 
lic bath. 

Dead  Pass. — See  pages  405  and  420. 

Dead  Roller. — See  page  407. 

Dead  Soft  Annealing. — See  pages  232  and  509. 

Dead  Soft  Steel.— See  page  455. 

Dead  Steel. — Steel,  page  144. 

Dead  Weight  Test— See  page  477. 

Dean  Process. — See  Hardening. 

Decalescent  Point. — See  page  265. 

Decarbonization. — See  page  382. 

Decarburization. — See  page  382. 

Decarburizing  Process. — For  malleable  castings:  see  page  258. 

Decomposition. — See  page  89. 

Decremental  Hardening. — See  pages  9  and  228. 

Decrepitation. — The  action  of  certain  salts  or  minerals  when  small 
fragments  fly  apart  with  a  cracking  sound  on  being  heated. 

Decrystallization. — See  page  281. 

Deep  Seam. — See  page  489. 

Deep-seated  Blowholes. — See  page  55. 

Defective  (noun — Eng.). — Waste  or  scrap  material. 

Defective  Welds. — See  page  502. 

Deficit  Substance. — See  page  266. 

Definite  Alloy. — See  page  4. 

Definite  Proportions,  Law  of. — See  page  84. 

Deflection. — Under  drop  test:  see  page  481. 

Deflection  Tests. — See  page  477. 

Deflocculated. — Brought  to  an  extremely  fine  state  of  division. 

Deformation. — (i)  General:  see  page  126;  (2)  energy  of:  see  page 
481. 

Deformation  Figure. — See  page  126. 

Deformed  Bar. — Bars  of  irregular  section  used  in  reinforced  con- 
crete construction. 

Degree  of  Heat. — See  page  199. 

Degasified.— See  page  55. 

Deighton  Converter. — See  page  23. 

Deliquesce ;  Deliquescence. — See  Water. 

Delivery. — Of  patterns:  see  page  296. 

Delta  (5)  Iron. — See  page  272. 

Demenge  Process. — See  page  8. 

Dempster  Process. — For  the  recovery  of  tar  and  ammonia  from  the 
gas  of  a  blast  furnace  using  raw  coal. 

Dendrite;  Dendritic  Crystal. — See  page  55. 

Dendritic  Interlocking. — See  page  282. 

Density. — Or  specific  gravity;  the  ratio  between  the  weight  of  a 
unit  volume  of  a  given  substance  and  that  of  a  unit  volume  of  some 
other  substance  taken  as  a  standard  under  standard  conditions 
of  temperature  and  pressure.  The  specific  gravity  of  solids  and 
liquids  is  found  by  dividing  their  weight  by  that  of  an  equal 
volume  of  water.  For  gases,  air  or  hydrogen  is  taken  as  the 
standard. 

Dephosphorization. — See  page  382. 


DEPOSITION  METHODS— DILUTION  133 

Deposition  Methods  of  Etching. — See  pages  286  and  288. 

Depuration  (rare). — Purification. 

Desch's  Iron -Phosphorus  Diagram. — See  page  272. 

Deseaming  Process. — See  page  418. 

Deshayes'  Formulae. — For  elongation:  see  page  338. 

Desiccation. — See  pages  30  and  499. 

Desiliconization. — See  page  382. 

Destructive  Distillation. — Distillation  in  a  closed  retort,  i.e., 
without  access  of  air.  It  is  applied  to  carbonaceous  material 
from  which  it  is  desired  to  drive  off  the  volatile  matter  without 
allowing  combustion  to  take  place,  or  only  to  a  very  limited 
extent. 

Destructive  Test. — See  page  467. 

Desulphurization. — See  page  382. 

Detail  Fracture. — See  page  179. 

Detinned  Scrap. — Tin-plate  scrap  from  which  nearly  all  of  the  tin 
has  been  removed. 

Detmold  Process. — See  page  385. 

Detrusion. — See  page  337. 

Devil. — See  page  298. 

Dezincification. — See  page  106. 

Diagonal  Cleavage. — See  page  124. 

Diagram. — See  Curve. 

Diameter. — In  measuring  magnifications. 

Diamond. — Form  of  carbon :  See  Carbon. 

Diamond  Pass. — See  page  405. 

Diamond  Rolling. — See  page  412. 

Diamond  Theory. — Of  hardening:  see  page  280. 

Diatomaceous  Earth. — See  page  396. 

Diatomic. — See  page  87. 

Dibasic. — See  page  87. 

Dick  Process. — A  process  for  making  all  kinds  of  metallic  sections, 
especially  those  difficult  to  roll  or  forge,  by  forcing  hot  and  plastic 
metal  through  a  die. 

Die. — In  forging:  see  page  195. 

Die  Plate. — In  wire  drawing:  see  page  507. 

Die  Temper. — See  Temper. 

Diehl-Faber  Process. — See  page  97. 

Differential  Cooling. — See  page  228. 

Differential  Freezing. — See  page  266. 

Differential  Hardening. — See  page  228. 

Differential  Heating. — See  page  228. 

Differential  Thermometer. — See  page  205. 

Differential  Thermoscope'. — See  page  205. 

Differentiation. — In  segregation:  see  page  56. 

Difficult  Cleavage. — See  page  1 24. 

Diffusion. — (i)  General:  see  Solution;  (2)  of  carbon  in  solid  solu- 
tion: seepage  213. 

Dilatation. — Expansion  or  distension. 

Dilatation  Method. — For  determining  critical  points:  see  page  265. 

Dilatometer. — See  page  483. 

Dilution. — In  cementation:  see  page  70. 


134  DILUTION  PYROMETERS— DIRECT  PROCESSES 

Dilution  Pyrometers. — See  page  210. 

Dimetric  System. — Of  crystallization:  see  page  120. 

Diminution. — Lessening  or  reduction. 

Dimorphism. — See  page  121. 

Dinas  Brick. — See  page  395. 

Dip  Roof. — The  depressed  (concave)  roof  first  adopted  for  open 
hearth  furnaces,  since  superseded  by  the  present  convex  roof. 

Dipping. — Of  tin  plates:  see  page  432. 

Direct. — Without  any  intermediate  stage  or  condition,  e.g.,  direct 
process,  where  the  ore  is  reduced  to  malleable  iron  or  steel  with- 
out first  being  made  into  cast  iron. 

Direct  Bloom. — Made  by  some  direct  process. 

Direct  Driven  Rolls. — See  page  407. 

Direct  Firing  Stove. — See  page  34. 

Direct  Heating  Furnace. — See  page  181. 

Direct  Metal.— See  page  36. 

Direct  Ore  Process. — See  below. 

Direct  Process. — (i)  Sometimes  applied  to  the  use  of  direct  metal, 
but  undesirably;  (2)  for  by-product  recovery:  see  page  96. 

Direct  Processes. — (i)  Those  in  which  wrought  iron  or  spongy  iron 
is  made  directly  from  the  ore,  and  either  used  as  such  or  converted 
into  steel,  usually  by  melting  it  with  cast  iron,  more  rarely  by 
cementing  it  with  carbonaceous  matter,  or  in  which  weld  or  even 
ingot  steel  (low  or  high-carbon  steel)  is  made  directly  from  the 
ore  (Howe),  sometimes  referred  to  as  direct  ore  process;  (2) 
rarely,  the  use  of  direct  metal  in  connection  with  the  open  hearth 
or  the  Bessemer  process. 

Direct  processes  may  be  classified  (Howe)  according  to: 

I.  Temperature: 

(a)  Sponge  making  processes:   where  the  temperature 
is  so  low  that,  while  the  iron  is  reduced,  it  is  not 
thoroughly  welded  together. 

(b)  Balling  heat  processes:   where   the  temperature  is 
sufficient  to  allow  the  iron  to  ball  or  weld  together. 

(c)  Steel  melting  heat  processes :  where  the  temperature 
is  sufficient  to  melt  the  product.     If  in  a  shaft  furnace, 
cast  iron  results.     It  is  applicable  only  in  a  reverbera- 
tory  furnace  or  a  crucible. 

II.  Action  of  fuel: 

1.  Heating  fuel  also  serves  for  deoxidation: 
(a)  Solid  fuel. 

(&)  Gaseous  fuel. 

2.  Separate  fuel  used  for  deoxidation. 

(c)  Ore  is  enclosed  in  externally  heated  retorts. 

(d)  Heated  by  a  current  of  hot  gas  passing  through 
it. 

(e)  Treated  in  open  reverberatories. 

The  furnace  principally  used  was  of  various  types  and  modifica- 
tions, and  was  called  a  bloomary  (sometimes  bloomery,  block 
oven,  block  furnace)  or  forge.  Forge  was  also  the  name  used 
for  the  heating  furnace  and  the  hammer,  or  for  the  whole  plant 


DIRECT  PROCESSES  1 3  5 

consisting  of  the  furnace,  a  blowing  engine,  and  a  hammer. 
"The  sides  are  iron  plates,  the  hair  plate  at  the  back,  the  cinder 
plate  at  the  front,  the  tuyere  plate  (through  which  the  tuyere 
passes)  at  one  side  (its  upper  part  being  called  in  some  bloomaries 
the  merrit  plate),  the  fore-spar  plate  opposite  the  tuyere  plate 
(its  upper  part  being  the  skew  plate),  and  the  bottom  plate  at  the 
bottom.  The  boot  is  the  joint  connecting  the  tuyere  or  nozzle 
with  the  blast  main,  usually  made  of  tin  or  leather.  The  tongs 
with  which  the  blooms  are  handled  were  called  (U.S.)  grampus" 
(Raymond). 

A  type  originally  like  the  stiickofen  (see  below),  but  later  used 
for  producing  either  wrought  iron  or  cast  iron,  and  resembling  a 
crude  blast  furnace,  was  termed  blauof en,  blau  furnace,  or  blue 
furnace ;  a  flussof en  was  strictly  a  primitive  blast  furnace. 

The  product,  extracted  as  a  lump  of  wrought  iron  mingled 
•with  slag,  was  called  a  loup  (loop),  bloom  or  ore  bloom,  but 
sometimes  the  two  latter  terms  were  applied  only  after  it  had 
been  worked;  ancony  was  the  old  name  for  a  bloom  which  had 
been  partly  worked  under  a  hammer.  EncrenSe  (Fr.)  is  the 
first  shape  given  to  a  bar  of  iron  from  the  forge.  The  mass  is 
forged  down  in  the  middle  to  the  dimensions  of  the  finished  bar, 
leaving  both  ends  unforged  (ancony).  A  marquette  d'encrenee 
is  an  encr6n6e  with  one  of  the  ends  forged.  These  definitions  are 
given  by  Grignon  (Osmond).  In  the  most  carburized  bars  from 
direct  steel,  when  the  drawing  out  (under  the  hammer)  has  not 
been  pushed  very  far,  there  develop  under  these  conditions  a 
great  number  of  small,  fine  transverse  cracks,  on  the  walls  of 
which  can  be  seen,  after  breaking,  concentric  zones  formed  by  the 
temper  colors.  The  name  roses  is  given  to  these  colorations,  and 
rose  steel  to  the  metal.  This  is  forged  and  then  quenched 
while  still  hot  to  classify  it  by  the  fracture;  the  less  carburized 
it  is  the  coarser  the  grain  (Resser). 

"No  forges  for  the  manufacture  of  blooms  and  billets  direct 
from  iron  ore  have  been  in  operation  in  the  United  States  since 
1 901,  in  which  year  the  blooms  and  billets  so  made  amounted  to 
2310  gross  tons,  against  4292  tons  in  1900  and  3142  tons  in 
1899.  All  the  Catalan  forges  in  the  South  have  been  abandoned; 
so  have  those  in  the  North  and  West."  (Annual  Statistical  Re- 
port of  the  American  Iron  &  Steel  Association,  1908,  p.  78). 

The  production  of  malleable  iron  direct  from  the  ore  has  proved 
a  most  attractive  field  for  metallurgists  and  inventors,  and  many 
attempts  have  been  made  to  devise  a  process^  which  would 
accomplish,  in  one  operation,  the  same  result  which  is  obtained 
by  the  blast  furnace  combined  with  some  one  of  the  refining  proc- 
esses. As  a  matter  of  logic  it  does  not  seem  reasonable  to  pro- 
duce iron  containing  a  greater  proportion  of  carbon  and  impuri- 
ties than  is  desired,  and  subsequently  remove  the  excess.  The 
difficulties  have  been  that  in  the  direct  process  the  product  can- 
not be  obtained  in  a  fluid  state  as  carbon  is  then  greedily  taken  up, 
and  this,  on  account  of  its  cheapness  and  availability  is  practi- 
cally the  only  substance  used  for  reduction  and  heating.  Mate- 
rials in  a  solid,  more  particularly  in  a  pasty  and  hot  condition, 


136  DIRECT  PROCESSES 

cannot  compare,  in  ease  of  handling,  with  fluids,  and  this  alone 
would  be  sufficient  to  account  for  the  lack  of  success  with  which 
direct  processes  have  met.  Furthermore,  few  ores  are  sufficiently 
pure  to  permit  of  their  use  for  direct  processes  without  prelimi- 
nary treatment. 

The  principal  advantages  and  disadvantages  may  be  summar- 
ized as  follows:  .. 

Advantages : 

(a)  An  iron  nearly  free  from  carbon  in  one  operation. 

(b)  Removal  of  phosphorus,  but  at  a  heavy  cost  of  iron. 
|  .   '.   (c)  Employment  of  cheap  fuel. 

Disadvantages : 

(d}  Product  not  fluid. 

(e)  Loss  of  iron  through  reoxidation  or  imperfect  deoxidation. 

(/)  Heterogeneousness  and  carburization  of  product. 

(g)  Absorption  of  sulphur. 

(h)  Heavy  outlay  for  labor. 

(i)  Rich  and  cheap  ores  necessary. 

As,  in  most  cases,  heating  and  reduction  are  performed  by  the 
fuel  in  contact  with  the  ore,  there  is  danger  where,  as  in  the  case  of 
the  old  high  bloomary,  the  height  of  the  furnace  is  considerable, 
that  not  only  will  the  ore  be  reduced,  but  also  carburized  to 
such  an  extent  as  to  produce  cast  iron.  After  the  iron  has  been 
reduced  to  the  metallic  state  it  will  absorb  carbon,  depending  on 
the  length  of  time  it  is  in  contact  with  the  fuel  and  on  the  tem- 
perature. It  is  therefore  necessary  to  keep  the  furnace  from  get- 
ting too  hot,  and  also  to  hasten  the  operation  as  much  as  possible. 

If  a  considerable  amount  of  the  ore  is  not  reduced,  the  resultant 
slag  is  very  basic,  and  consequently  possesses  the  property  of 
holding  most  of  the  phosphorus  and  preventing  it  from  being 
reduced  and  taken  up  by  the  metallic  iron.  On  the  contrary, 
when  reduction  is  strong,  there  will  be  less  iron  in  the  slag  which 
will,  accordingly,  be  less  basic,  and  phosphorus  is  then  reduced. 

Another  advantage,  viewed  from  the  standpoint  of  quality  but 
not  of  cost,  of  having  the  slag  very  basic,  is  that  less  sulphur  is 
absorbed  by  the  metal.  While  the  charge  is  descending,  any 
pyrites  will  be  partially  roasted,  and  will  lose  one  atom  of  its 
sulphur: 

FeS2  +  O2  +  Heat  =  FeS  +  SO2 

The  other  atom  of  sulphur  will  not  be  much  affected  on  account 
of  the  excess  of  carbon  present,  which  of  course  tends  to  make  a 
reducing,  and  not  an  oxidizing,  atmosphere.  The  remaining  sul- 
phur will  be  largely  taken  up  by  the  metal,  depending  consider- 
ably on  the  nature  of  the  slag.  With  sulphur  dioxide  in  the 
products  of  combustion,  the  reaction  may  occur: 

SO2  +  2C  =  S  +  2CO 

The  necessary  carbon  may  be  obtained  either  from  the  fuel  or 
from  that  in  the  metal  itself. 

It  should  be  noted  that,  in  direct  processes,  the  phosphorus  is, 


DIRECT  PROCESSES  1 3  f 

to  a  great  extent  under  control,  and  that  the  sulphur  is  not,  while 
just  the  reverse  is  true  of  the  blast  furnace.  In  the  latter  case,  a 
large  amount  of  lime  is  charged  to  remove  the  sulphur,  and  as  the 
resultant  slag  is  very  infusible,  a  high  temperature  is  required, 
and,  consequently,  all  the  iron  and  phosphorus  are  reduced  and 
the  former  is  highly  carburized  (after  Howe). 

In  the  Adams  process  (sometimes  called  Blair-Adams  process) 
ore  in  lumps  3"  cube  and  smaller,  sometimes  mixed  with  about  5 
%  of  solid  fuel,  and  in  vertical  chambers  above  an  open  hearth 
furnace,  is  heated  and  reduced  by  a  current  of  hot  gas.  It  passes 
thence,  either  continuously  or,  better,  one  chamberful  at  a  time, 
into  a  chute,  and  thence  into  a  bath  of  molten  cast  iron  in  the  open 
hearth  furnace,  diluting  and  probably  also  oxidizing  the  carbon 
and  silicon  of  the  bath,  quite  as  in  common  open  hearth  practice 
(Howe). 

The  American  bloomary  process  (American  forge  or  Cham- 
plain  forge),  resembling  the  Catalan  process  in  its  general  fea- 
tures, differs  from  it  in  that  the  ore  is  charged  wholly  in  a  fine 
state  and  mixed  with  charcoal,  instead  of  chiefly  in  lumps  and  in 
a  separate  column  (Howe) .  The  furnace  is  somewhat  higher,  and 
the  bottom  plate  is  of  cast  iron  water-cooled. 

In  A.  E.  L.  Belford's  process  the  ore,  pulverized  and  well  mixed 
with  charcoal  or  other  carbonaceous  matter,  and  with  or  without 
the  addition  of  fluxes,  is  heated  in  a  tubular  or  other  suitably 
shaped  vessel.  It  is  then  transferred,  with  as  little  cooling  as 
possible,  to  crucibles  and  melted  down.  In  a  modification,  where 
the  initial  product  is  -evidently  obtained  in  a  fused  and  carburized 
condition,  it  is  transferred  by  a  closed  runner  to  a  decarburizing 
chamber,  heated  from  without,  where  it  is  acted  upon  by  decar- 
burizing gases  or  steam. 

In  the  Berner  process  a  special  shaft  furnace  is  employed  with 
tuyeres  at  different  levels,  and  divided  into  two  parts  by  a  verti- 
cal partition.  On  one  side  ore  is  smelted  to  pig  iron  with  solid 
fuel,  while  on  the  other,  ore  is  reduced  to  spongy  iron  with  reduc- 
ing gases.  The  spongy  iron  is  dissolved  in  the  mloten  pig  iron  at 
the  bottom,  diluting  the  impurities  to  form  a  sort  of  steel  which  is 
run  into  a  reverberatory  furnace,  forming  a  fore-hearth  to  the 
shaft  furnace,  where  the  treatment  is  completed. 

The  Blair  process,  also  called  Blair's  iron  sponge  process,  is 
an  improvement  over  Chenot's  process,  in  which  small  lumps  of 
ore  mixed  with  charcoal  are  heated  externally  in  a  retort  about 
4%  feet  in  diameter  and  40  to  50  feet  high,  the  heating  taking 
place  at  the  top,  the  sponge  then  descending  into  a  cooling  cham- 
ber, and  being  finally  taken  out  at  the  bottom.  Later  Blair  dis- 
covered that  the  addition  of  about  5  %  of  lime  to  the  ore  greatly 
hastened  deoxidation.  The  earlier  apparatus  consisted  of  three 
vertical  retorts,  but  in  the  later  form  there  was  only  one,  and 
producer  gas  was  used  to  heat,  first  externally,  and  then  near  the 
top,  by  passing  directly  through  the  ore.  There  was  the  cooling 
chamber  as  before.  The  sponge  when  drawn  from  the  reducing 
furnace  was  quite  cool,  so  that  it  did  not  reoxidize.  It  was 
squeezed  under  a  pressure  of  30,000  pounds  to  the  square  inch  into 


138  DIRECT  PROCESSES 

cylindrical  blooms.  Later  only  the  fine  sponge  was  compressed, 
the  lumps  being  shoveled  into  the  open  hearth  furnace,  for  which 
all  the  material  was  designed  to  replace  scrap.  He  also  combined 
the  sponge  with  charcoal  or  tar  to  lessen  the  proportion  of  cast 
iron  needed  in  the  open  hearth  process  (Howe). 

Bull's  process:  This  so-called  direct  process  was  hardly  one 
at  all,  but  rather  an  ill-advised  attempt  to  replace  the  whole  of  the 
solid  fuel  of  the  blast  furnace  with  superheated  water  gas  (Howe). 

The  Cadinho  furnace  is  cylindrical  and  of  circular  or  slightly 
oval  section,  about  3  feet  high  and  i  foot  in  diameter  (inside), 
and  has  one  tuyere  with  air  supplied  by  a  trompe.  The  furnace 
is  filled  with  charcoal,  and  after  it  is  ignited  and  the  furnace  hot, 
alternate  layers  of  charcoal  and  moistened  powdered  ore  are  in- 
troduced. After  blowing  for  about  i%  to  i%  hours  the  fire  is 
allowed  to  go  down  and  the  bloom  is  extracted  through  a  hole  at 
the  bottom.  The  reduction  is  very  imperfect,  the  yield  being 
about  22%  of  the  ore. 

The  Carbon  Iron  Company's  process  (Iron  Company's  process) : 
Iron  ore  is  deoxidized  on  the  carbonaceous  hearth  of  an  open 
reverberatory  furnace  by  means  of  graphitic  anthracite  or 
retarded  coke  (see  Coke)  with  which  it  is  mixed.  These  reducing 
agents,  in  that  they  themselves  become  oxidized  only  very  slowly, 
indeed  reduce  the  iron  less  rapidly  than  charcoal  or  common  coke; 
but  after  reduction  is  effected  they  resist  oxidation,  and  so  persist 
and  remain  to  protect  the  reduced  iron  from  oxidation.  The 
reduced  iron  is  then  balled  and  put  in  an  open  hearth  furnace,  or 
squeezed  for  rolling  into  wrought  iron  (Howe).  Blooms  made  by 
this  process  were  called  carbon  blooms  or  sponge  blooms.  The 
original  process  (Eames  process)  employed  Rhode  Island  graph- 
itic carbon,  and  in  its  later  form  had  a  number  of  modifications, 
including  moistening  the  carbonaceous  reducing  material  with 
lime  or  some  similar  inert  substance  to  retard  its  oxidation. 

Catalan  process  or  Catalan  forge  process :  The  furnace  usually 
consists  of  an  open  hearth  of  about  28"  depth  to  the  rear  wall, 
and  30"  width,  and  provided  (usually)  with  one  tuyere  inserted 
2  feet  below  the  level  of  the  top  of  the  fuel.  The  casing  is  of 
cast  iron,  double  and  water-cooled.  Above  the  hearth  is  a  stack 
to  carry  away  the  products  of  combustion.  The  hearth  is  open 
at  the  front  like  an  ordinary  open  fireplace.  The  blast  is  supplied 
under  a  pressure  of  from  i%  to  2  pounds  per  square  inch,  and 
heated  to  a  temperature  rarely  if  ever  measured  but  generally  sup- 
posed to  be  600°  to  800°  F.  (315°  to  430°  C.).  The  heating  pipes 
are  bent  U-shaped  tubes  placed  in  the  stack.  The  tuyere  is 
either  pointed  horizontally  or  slightly  inclined  downward.  The 
furnace  is  first  filled  with  charcoal,  which  is  lighted,  and  the  blast 
turned  on.  When  the  whole  is  well  ignited,  the  ore,  calcined  and 
coarsely  pulverized,  is  sprinkled  with  a  shovel  over  the  surface  of 
the  fuel  in  small  quantities,  and  at  short  intervals  basketfuls  of 
charcoal  are  added  as  the  fire  burns  down.  The  ore  is  deoxidized 
by  the  fuel  as  it  works  downward,  and  the*metal  finally  collects  in 
an  unfused  pasty  mass  at  the  bottom  of  the  hearth,  like  a  great 
sponge.  The  cinder  fills  its  pores  as  a  liquid  bath,  and  is  tapped 


DIRECT  PROCESSES 


139 


off  occasionally  at  the  front.  A  mass  of  iron  weighing  about  300 
pounds  is  formed  in  about  3  hours.  This  is  lifted  out  from  under 
the  fuel  and  is  worked  under  a  hammer  into  a  bloom  or  loup  which 
is  reheated  when  necessary  at  the  charcoal  fire.  One  furnace  or  fire 
is  expected  to  yield  from  i  ton  to  2500  pounds  per  day.  About 
3500  to  5000  pounds  of  charcoal,  and  i?$  to  i%  tons  of  selected 
ore  (equivalent  to  from  2^  to  4  tons  of  ore  as  mined)  are  used 
per  ton  of  blooms  (Thurston). 


FIG.   15. — Catalan  forge  (Thurston,   "Iron  and  Steel"). 

In  Chenot's  process  washed  or  pure  ore,  agglutinized  with 
some  pasty  substance  (e.g.,  3  %  of  resin)  and  mixed  with  a  slight 
excess  of  charcoal,  was  charged  in  vertical  rectangular  retorts 
about  28^  feet  high,  6^  feet  long,  and  i  K  feet  wide,  the  width  in- 
creasing slightly  at  the  bottom.  The  upper  part  was  of  fire-brick 
surrounded  and  heated  by  a  series  of  vertical  flues,  connecting 
at  the  bottom  with  fireplaces,  and  open  at  the  top.  The  bottom 
was  of  sheet  iron,  water- jacketed  to  receive  and  keep  the  sponge 
out  of  contact  with  the  air  until  cold.  The  operation  was  con- 
tinuous. In  a  later  method  he  reduced  and  heated  the  ore  by 
passing  through  it  a  current  of  hot  carbonic  oxide  (producer  gas) 
in  the  same  style  of  apparatus. 

In  Clay's  process  red  hematite  ore,  crushed  to  lumps  not  larger 
than  a  walnut,  was  mixed  with  one-fifth  its  weight  of  charcoal  or 
other  carbonaceous  matter  and  subjected  to  a  bright  red  heat  in 
clay  retorts,  etc.,  until  the  iron  was  reduced  to  the  metallic  state. 
The  sponge  so  produced  was  then  transferred  to  a  puddling  fur- 
nace, with  or  without  the  addition  of  5  %  of  coke,  where  it  was 
balled.  The  process  was  slow  and  costly,  and  the  iron  produced 


140  DIRECT  PROCESSES 

Was  frequently  red  short.  He  also  mixed  ore  with  half  its  weight 
of  coal,  etc.,  and  heated  it  in  a  puddling  furnace  with  four  times 
its  weight  of  pig  iron  (Percy). 

In  the  Conley  process  crushed  and  magnetically  concentrated 
ore  is  mixed  with  carbon  and  heated  in  closed  retorts  (heated 
externally),  the  ore  and  the  reducing  agent  being  stirred  con- 
tinually. The  partially  reduced  ore  is  transferred  to  iron  cases 
where  it  is  allowed  to  cool  out  of  contact  with  the  air  and  is 
then  mixed  with  a  small  percentage  of  pitch,  molded  into  bricks 
and  melted  down.  In  a  later  modification  (Conley -Lancaster 
process)  the  ore,  in  heated  retorts,  is  reduced  by  intermixed 
solid  carbonaceous  matter,  or  by  a  gas  which  is  led  through  the 
retorts,  after  which  the  sponge  is  transferred  to  an  open  hearth 
furnace  with  as  little  exposure  to  the  air  as  possible. 

Edward  Cooper  process :  Iron  ore  in  a  column  is  heated  and 
reduced  by  a  current  of  hot  carbonic  oxide,  or  carbonic  oxide 
and  hydrogen.  These  gases  are  oxidized  to  carbonic  acid 
and  steam  by  the  oxygen  of  the  ore:  they  are  then  passed  through 
a  regenerator,  in  which  they  are  highly  heated,  and  thence 
through  a  bed  of  coal  or  other  fuel  in  which  they  are  again 
deoxidized  to  carbonic  oxide  and  hydrogen.  Still  remaining  in 
the  same  closed  circuit,  they  are  then  used  for  reducing  a  fresh 
portion  of  the  ore,  a  part  of  the  carbonic  oxide  and  hydrogen, 
however,  being  diverted  to  heat  the  regenerator  already  men- 
tioned (Howe). 

The  Corsican  process  is  similar  to  the  Catalan,  but  very 
much  cruder.  The  furnace  is  really  a  blacksmith's  forge  with 
one  tuyere.  About  10  cwts.  of  ore  are  placed  on  the  side  away 
from  the  tuyere  and  moistened  crushed  charcoal  is  packed 
between.  Care  is  taken  at  first  not  to  melt  the  ore.  Charcoal 
is  thrown  on  at  intervals,  and  finally  the  reduced  sponge  is  melted 
down,  and  the  bloom  extracted,  hammered,  etc.  The  process 
takes  about  24  hours  and  uses  about  9  parts  by  weight  of  char- 
coal to  i  of  iron  produced,  and  the  loss  of  iron  is  about  30%. 

The  De  Laval  process  consists  in  heating  a  mixture  of  pul- 
verized ore  and  carbonaceous  matter  in  a  rotating  cylinder, 
and  then  bringing  it  in  contact  with  a  powerful  electric  arc 
to  reduce  the  iron  to  the  metallic  state.  The  melted  iron  is 
transferred  into  a  large  and  highly  heated  furnace  where  it 
can  be  directly  made  into  steel,  or  from  which  it  can  be  cast 
into  molds  for  further  treatment. 

In  the  Du  Puy  process  about  116  pounds  of  ground  iron  ore, 
mixed  with  carbonaceous  matter  for  reduction  and  with  suitable 
fluxes  to  scorify  the  gangue,  is  enclosed  in  annular  sheet-iron 
canisters  about  13"  high,  15"  in  diameter,  and  weighing  6  pounds. 
The  charged  canisters  are  heated  to  bright  whiteness  (a  welding 
heat)  for  from  5^  to  10  hours  on  the  coke-covered  hearth  of  a 
common  open  reverberatory  furnace.  The  reduced  metal, 
still  in  its  canister,  may,  according  to  Du  Puy,  be  converted 
into  muck  bar  by  hammering  or  squeezing  and  rolling  and  then 
cut  up  and  treated  by  the  crucible  process:  it  may  be  charged  at 
once  in  the  open  hearth  process  with  or  without  (?)  cast  iron; 


DIRECT  PROCESES  141 

or  it  may  be  melted  down  with  cast  iron  in  the  furnace  in  which 
it  has  been  reduced  (Howe). 

In  J.  G.  von  Ehrenwerth's  process  high  carbon  iron  (pig 
iron)  is  melted  at  a  high  temperature  in  an  open  hearth  furnace; 
ore  is  added,  the  iron  in  which  is  reduced  by  the  carbon  of  the 
bath  and  dissolved  by  the  bath,  which  is  recarburized  with  solid 
carbon  in  the  furnace  itself,  or  in  a  pan,  or  in  a  small  blast  furnace. 
Ore  is  again  allowed  to  act  on  the  carburized  material,  and  the 
process  is  repeated  until  the  requisite  amount  of  iron  is  produced. 
The  slag  which  is  poor  in  iron  is  removed  from  time  to  time. 
The  higher  the  temperature,  the  more  satisfactory  is  the 
operation. 

In  the  Eustis  process  briquettes,  made  by  coking  fine  ore 
with  bituminous  coal,  were  to  be  melted  in  a  cupola,  with  the 
idea  that  the  phosphorus  would  not  be  reduced,  but  the  tendency 
would  be  to  reduce  the  phosphorus  and  also  to  produce  cast  iron. 

In  the  Gerhardt  process,  briquettes  composed  of  ore,  flux, 
carbonaceous  matter,  and  tar  were  heated  in  a  puddling  furnace, 
the  reduced  iron  being  balled,  etc. 

The  German  bloomary  was  like  an  early  form  of  Catalan 
forge.  The  product  was  sometimes  termed  German  steel, 
although  this  name  was  also  applied  to  wrought  iron  produced 
by  refining  pig. 

The  Graff  process  appears  to  be  practically  the  same  as 
the  Iron  Company's  process.  Coarsely  pulverized  coke,  treated 
with  a  wash  of  lime  or  clay,  is  mixed  with  ore  and  heated,  on  the 
hearth  of  a  reverberatory  furnace  lined  with  coke,  at  a  tempera- 
ture sufficient  to  slag  off  the  gangue.  The  iron  may  be  balled 
or  transferred  direct  to  the  bath  of  an  open  hearth  furnace. 

G.  Gunther's  process  consists  in  (i)  the  reduction  of  finely 
divided  ore  by  solid  carbon  at  a  low  temperature  to  avoid  slag- 
ging off  any  unreduced  ore;  (2)  the  transfer  to  a  receptacle  filled 
with  reducing  gases  to  complete  the  reduction;  and  (3)  fusion  of 
the  reduced  iron  with  coke  and  fluxes  in  a  shaft  furnace. 

The  Gurlt  process  consisted  in  deoxidizing  iron  ore  and  car- 
burizing  (?)  the  resulting  sponge  in  the  central  shaft  of  a  special 
type  of  furnace  by  passing  through  it  a  stream  of  hot  producer 
gas  from  producers  forming  part  of  the  furnace.  Here  the 
producer  gas  both  heats  and  deoxidizes  the  ore  which  is  unmixed 
with  solid  fuel.  The  hot  spongy  iron  was  drawn  through  a 
doorway  at  the  bottom  of  the  shaft,  to  be  balled,  or,  if  highly 
carbureted,  to  be  melted,  in  an  open  hearth  furnace  or  in  a  char- 
coal hearth  (Howe). 

The  Harvey  process,  similar  to  Renton's,  consisted  in  heating 
coarsely  powdered  ore  with  charcoal  on  inclined  steatite  shelves 
connected  with  a  balling  furnace,  and  heated  by  a  passing  flame. 
The  deoxidized  ore  was  transferred  to  the  hearth  of  the  balling 
furnace  and  balled  (Howe). 

Hawkins  process  was  to  cement  (heat)  iron  ore  in  lumps 
surrounded  with  charcoal. 

Gustave  Hofer's  process  employs  a  special  type  of  furnace 
having  the  shape  of  a  truncated  cone  with  the  smaller  end 


142  DIRECT  PROCESSES 

downward,  and  mounted  on  trunnions  so  it  can  be  tipped.  It  is 
lined  with  refractory  material,  and  inside  is  a  separate  refractory 
chamber  between  which  and  the  lining  are  a  number  of  gas 
passages.  This  inner  or  reducing  chamber  is  provided  with  two 
pipes,  an  upper  for  tapping  the  slag,  or  the  iron  by  tipping  the 
furnace,  and  a  lower  one  for  introducing  gases,  and  for  tapping 
the  iron.  The  main  or  outer  vessel  is  provided  with  inlets  for 

§is  and  air  which  burn  and  go  up  through  the  gas  passages. 
re  and  coal  are  charged  in  the  reducing  chamber,  and  are  heated 
by  the  burning  gases  on  the  outside.  When  the  reduction  and 
smelting  are  complete,  the  slag  is  tapped  off,  the  valve  in  the 
bottom  of  the  furnace  opened,  and  gases  blown  into  the  bath 
of  metal  to  purify  it.  The  furnace  may  also  be  fired  from  the 
outside. 

Husgafvel's  high  bloomary  or  continuous  stiickofen  was  a 
tall  shaft  furnace  about  26  feet  high,  with  double  air-cooled 
walls  between  which  the  blast  was  preheated.  It  had  a  movable 
hearth  with  four  water-cooled  tuyere  holes  on  each  of  the  two 
opposite  sides  on  two  levels.  The  blast  was  introduced  in  the 
lower  holes  first  and,  as  the  hearth  filled  up,  these  were  plugged 
up  and  the  upper  ones  used.  When  the  hearth  was  filled  up  to 
these,  the  blast  was  stopped  and  the  hearth  removed.  A  fresh 
hearth  was  put  in  place  and  the  process  continued. 

The  Imperatori  process  consists  essentially  in  adding  briquettes 
of  iron  ore  and  coal  to  the  bath  of  metal  in  an  open  hearth  furnace. 

The  Ireland  process  has  to  do  with  melting  sponge  in  a  cupola 
furnace. 

The  Irving  process  is  conducted  in  an  electric  furnace.  A 
continuous  shower  of  ore  (fine  magnetite)  and  limestone  is  passed 
from  an  upper  stack  through  a  reduction  chamber,  in  which  the 
ore  is  partly  reduced  by  ascending  carbon  monoxide,  to  a  crucible 
at  the  bottom  in  which  the  reduction  is  completed  by  means  of 
finely  powdered  coke  introduced  at  the  top  of  the  crucible  arch. 
The  steel  produced  in  eight  experimental  heats  contained  from  0.12 
to  0.35  %  carbon. 

The  Italian  process  is  similar  to,  but  less  perfect  than,  the 
Catalan  process.  The  hearth  is  smaller  and  shallower.  The 
tuyere  is  less  inclined  and  enters  the  fire  nearly  in  a  line  with 
the  opposite  wall.  The  yield  was  only  up  to  40  or  45  %. 

The  Jones  step  process,  as  applied  to  iron  ores  provides  for 
metallizing  (reducing)  the  oxides  by  subjecting  them  in  a  heated 
condition,  without  fusion,  to  a  reducing  atmosphere.  It  is 
claimed  that  a  product  consisting  of  97  %  pure  iron  can  be  secured 
which  is  suitable  preferably  for  briquetting  and  charging  in  an 
open  hearth  furnace,  or  by  melting  in  a  cupola  carbon  can  be 
added  for  the  manufacture  of  castings.  In  preparing  the  ore  for 
treatment,  it  is  first  crushed  and  passed  Over  a  f  inch  screen.  It  is 
mixed  with  coal  and  placed  in  the  first  of  a  pair  of  cylindrical 
sheet  iron  furnaces  arranged  tandem.  The  charge  may  be 
preheated  to  about  700°  F.  (370°  C.)  by  an  oil  flame  at  which  tem- 
perature the  reducing  action  begins  and  the  preheating  flame  is 
then  shut  off.  The  first  stage  consists  largely  of  heating  to  about 


DIRECT  PROCESSES  143 

1500°  F.  (815°  C.),  with  attendant  volatilization  of  the  hydro- 
carbons in  the  coal  and  the  partial  reduction  of  the  ore  and  the 
formation  of  carbon  monoxide.  The  pressure  of  gas  causes 
circulation  and  forces  the  gas  into  the  second  furnace  where  a 
reducing  atmosphere  is  established  for  another  fresh  charge. 
When  the  action  in  the  first  tube  is  complete,  as  determined  by  a 
time  limit,  this  furnace  is  cut  off,  the  charge  dumped  and  quenched, 
the  same  as  coke,  and  jigged  to  separate  the  coke  from  the  metal- 
lic particles.  The  metallized  ore  is  then  crushed  in  rolls,  magnet- 
ically separated,  and  formed  into  briquettes,  either  by  pressure 
or  with  a  tar  binder.  The  two  furnaces  are  thus  alternately 
dumped  and  charged  (Iron  Age,  12/14/11). 

In  Francis  Knowle's  process  clean  ore  in  lumps  was  heated 
in  retorts  through  which  various  reducing  gases  were  passed. 

H.  Larkin's  process  employed  magnetite  which  was  crushed 
and  passed  through  a  magnetic  separator.  The  concentrates 
were  molded  into  bricks  with  carbonaceous  matter,  which 
were  then  placed  in  retorts  of  D-section,  externally  heated  with 
gas.  After  exposure  to  a  red  heat  for  24  hours,  the  iron  was  ob- 
tained as  a  powder. 

In  the  Lash- Johnson  process  ore  and  carbonaceous  matter 
are  ground  together  to  a  fine  powder,  and  mixed  with  a  binding 
material  such  as  sodium  silicate  or  tar.  The  resultant  material, 
after  drying  and  coking,  is  spread  on  the  hearth  of  a  reverbera- 
tory  furnace.  The  surface  is  protected  with  a  mixture  of  two- 
thirds  glass  and  one-third  carbon,  and  the  slag,  fairly  rich  in 
oxide,  which  is  tapped  off,  is  claimed  to  carry  much  of  the  phos- 
phorus with  it. 

The  Laureau  process  aims  to  deoxidize  iron  ore  with  natural 
gas,  and  to  prevent  the  deposition  of  carbon  which  occurs  when 
fuel  is  passed  directly  through  hot  ore.  To  prevent  this,  before 
admitting  the  gas  to  the  ore  column,  it  is  mixed  with  enough  air 
to  convert  its  carbon  into  carbonic  oxide,  and  the  mixture  is 
heated  to  the  temperature  at  which  carbon  tends  to  deposit. 
But  when  the  carbon  is  now  set  free,  instead  of  depositing  as  such, 
it  unites  with  the  oxygen  present,  and  we  have  a  mixture  of 
hydrogen  and  carbon  monoxide  (Howe). 

In  the  Leckie  process  briquettes  composed  of  coal  or  peat 
were  heated  and  deoxidized  in  chambers  connecting  with  an 
open  hearth  furnace  containing  a  bath  of  pig  iron  into  which 
they  were  then  transferred. 

Liebermeister  proposed  to  produce  steel  directly  in  a  blast 
furnace  by  interrupting  the  carburization  at  the  proper  moment. 

In  Samuel  Lucas*  earliest  process  ore  was  deoxidized  with 
carbonaceous  matter  in  a  furnace  similar  to  that  used  for  cementa- 
tion. The  sponge  obtained  was  melted  in  crucibles.  A  later 
method  was  to  heat  bars  of  wrought  iron  in  alternate  layers  with 
ore,  charcoal,  and  oxide  of  manganese  in  the  same  type  of  furnace. 

Matthiessen's  process  was  not  a  commercial  proposition 
but  simply  designed  to  obtain  chemically  pure  iron.  It  consisted 
in  fusing  together  pure  ferrous  sulphate  and  sodium  sulphate, 
washing  the  oxide  obtained,  and  reducing  it  by  heating  in  a 


144  DIRECT  PROCESSES 

stream  of  hydrogen,  the  resulting  sponge  being  compressed  in  the 
cold,  or  melted  in  lime  crucibles. 

David  Mushet's  process  was  about  the  same  as  the  first  one 
of  Lucas. 

In  the  native  forge  or  bloomary  process  (used  in  India  and 
the  East)  ore  and  charcoal  are  heated  in  a  small  clay  furnace 
with  either  natural  or  forced  draft.  From  20  to  120  Ibs.  of  iron 
are  produced  from  a  charge.  With  natural  draft  about  20  tuy- 
eres are  used,  and  with  forced  draft  there  are  3  tuyeres.  The 
bloom  is  reheated  and  hammered  to  free  it  from  slag.  Both  soft 
and  steely  iron  can  be  produced  according  to  the  charge. 

In  the  Neville  process  ore  and  carbonaceous  matter  are  charged 
into  the  upper  of  two  sets  of  chambers  through  which  the  gases 
from  the  furnace  pass  and  effect  a  partial  reduction.  The  charge 
is  then  dropped  into  the  lower  set  of  chambers,  and  thence  into 
the  hearth  of  the  furnace  where  it  is  balled. 

W.  E.  Newton's  process  consisted  in  piling  together  layers 
of  ore,  charcoal,  etc.,  and  flux  which  were  heated  in  a  suitable 
vessel  at  a  white  heat  for  about  48  hours.  The  reduced  iron 
was  melted  in  a  crucible  or  treated  in  a  puddling  furnace. 

The  Nyhammer  continuous  high  bloomary  consists  of  a  shaft 
1 6  feet  high  and  18"  wide,  from  the  bottom  of  which  covered 
flues  lead  to  closed  charcoal  hearths.  Ore  and  charcoal  are 
charged  in  the  hearth  continuously,  and  through  this  the  gases 
from  the  charcoal  hearths  pass  to  heat  the  charge.  The  propor- 
tion of  ore  to  charcoal  charged  in  the  shaft  is  regulated  so  that  the 
temperature  and  reducing  conditions  in  the  shaft  may  be  such  as 
to  deoxidize  the  ore  and  heat  the  resulting  sponge  strongly,  but  not 
to  carburize  or  to  soften  it.  The  hot  but  not  sticky  spongy  iron, 
together  with  the  residual  charcoal,  is  raked  from  the  bottom  of 
the  shaft  into  one  of  the  charcoal  hearths,  through  one  of  the 
flues  already  described.  In  this  hearth  the  spongy  iron  is  heated 
to  the  welding  point  and  balled,  fresh  lots  of  sponge  apparenty  be- 
ing raked  in  as  fast  as  the  iron,  balling,  sinks,  till  enough  for  a  bloom 
has  reached  the  hearth,  when  raking  ceases  or  is  diverted  to 
another  hearth.  The  melted  slag  is  tapped  from  the  hearth,  the 
iron  worked  into  a  bloom,  drawn  and  hammered  (Howe). 

The  Osmund  process  employed  a  rectangular  furnace  (Osmund 
furnace)  about  8  feet  high,  and  provided  with  one  tuyere,  and  a 
tapping  hole  for  running  off  the  slag.  It  was  built  of  masonry, 
which  was  packed  around  with  earth  held  in  place  by  a  timber 
casing.  Calcined  phosphoric  bog  or  lake  ores  were  smelted  with 
charcoal  much  as  in  the  Catalan  process,  and  the  bloom  (osmund) 
was  extracted  by  removing  the  front  of  the  furnace.  The  loss 
was  about  33  to  50%. 

The  Otto  process  consists  in  reducing  ore  by  gas  under  high 
pressure  in  an  externally  heated  horizontal  retort,  the  gas 
for  reduction  being  subsequently  used  for  heating  the  retort. 

In  Ponsard's  process,  which  resembled  Siemen's  earlier 
process,  several  fireclay  retorts,  8"  in  diameter  and  40"  high, 
were  placed  in  a  reverberatory  furnace,  their  mouths  being 
fitted  to  openings  in  the  roof,  their  lower  parts  open  or  perforated 


DIRECT  PROCESSES  145 

and  resting  upon  the  hearth  which  had  gutters  leading  to  a 
central  sump.  In  the  retorts  is  charged  ore  with  flux  and  about 
12  %  of  carbon  for  deoxidation  and  carburization.  The  reduced 
ore,  melting,  runs  through  the  holes  in  the  bottoms  of  the  retorts 
and  collects  in  the  sump  (Howe). 

Ramdohr's  process  consisted  essentially  in  dropping  fine 
ore  through  a  furnace  of  special  construction,  reduction  being 
effected  by  carbonic  oxide. 

In  Jacob  Reese's  process  ores  were  melted  in  a  cupola,  and 
petroleum  was  blown  through  them.  He  expected  the  phos- 
phorus to  be  given  off  as  phosphoreted  hydrogen. 

In  the  Rinton  process  a  furnace  was  employed  resembling 
an  ordinary  puddling  furnace,  with  a  vertical  fire-brick  retort 
or  chamber  at  one  end,  surrounded  externally  by  the  flues 
from  the  furnace  by  which  it  was  heated.  Broken  ore  and 
coal,  in  the  proportion  of  i  to  3,  are  charged  in  the  retort,  and 
when  the  ore  is  sufficiently  reduced  the  spongy  iron  is  discharged 
upon  the  hearth  of  the  furnace  and  balled. 

In  G.  Roger's  process  the  iron  ore  mixed  with  coal  is  heated 
and  reduced  in  a  rotating  cylinder,  externally  heated,  and  situated 
above  a  puddling  furnace  into  which  the  resulting  sponge  is 
dropped  and  balled. 

The  Rudolphs-Landin  process  consists  in  making  briquettes  of 
fine  ore,  carbonaceous  material,  and  flux  as  required,  which  are 
dried,  and  the  iron  reduced  while  being  passed  through  a  long 
furnace.  The  reduced  briquettes  are  dropped  into  a  bath  of 
molten  metal  covered  with  slag  contained  in  a  reverberatory  fur- 
nace, and  portions  of  the  bath  are  transferred  from  time  to  time 
to  an  open  hearth  furnace  and  finished. 

In  the  Sarnstrom  process,  a  modification  of  the  Osmund  or  the 
Catalan  process,  the  furnace  consists  of  a  vertical  reduction  shaft 
connected  with  a  number  of  hearths  by  small  passages  which  can 
be  closed  by  dampers  which  are  provided  with  small  holes  so  the 
gases  from  the  hearths  may  pass  through  the  shaft.  Ore  and 
charcoal  are  charged  at  the  top  of  the  shaft,  and  during  its  des- 
cent the  ore  is  reduced  and  the  iron  sponge  produced  is  worked 
and  balled  in  the  hearths. 

In  A.  Sattman  and  A.  Homatsch's  process  ore  is  heated  (cal- 
cined if  necessary)  by  the  combustion  of  gas  in  a  special  type  of 
shaft  furnace;  reduction  is  effected  by  passing  reducing  gas  alone 
through  the  charge,  the  resulting  sponge  being  melted  in  a 
chamber  at  the  bottom  of  the  shaft,  and  connecting  with  a 
closed  chamber  in  which  solid  fuel  .is  burned.  The  fluid  iron, 
somewhat  carburized,  may  be  run  directly  into  an  open  hearth 
furnace  and  finished,  or  partial  removal  of  the  carbon  may  be 
effected  by  hot  oxidizing  gases  acting  on  the  metal  as  it  runs 
from  the  melting  chamber  to  a  receiving  chamber.  The  process  is 
intended  to  be  worked  either  intermittently  or  continuously. 

In  the  Schmidhammer  process,  apparently  following  out  the 

idea  of  the  Nyhammer  furnace,  a  special  form  of  continuous 

stiickofen  was  proposed.     The  shaft  is  charged  continuously  with 

ore  and  enough  charcoal  for  deoxidation;  the  ore  is  deoxidized 

10 


146  DIRECT  PROCESSES 

during  the  descent;  the  temperature  is  raised  to  the  welding  point 
by  hot  blast  and  hot  water  gas  blown  through  the  tuyeres;  the 
spongy  iron  is  balled  through  working  openings;  and  the  balls  are 
drawn  from  a  forcrhearth  on  lifting  the  door.  The  distinctive 
features  are  substitution  of  hot  gas  and  air  for  part  of  the  more 
costly  charcoal;  the  fore-hearth  and  the  door  which  permit  of 
formMg  and  drawing  the  balls  without  allowing  the  superincum- 
bent charge  to  slide  down  as  in  Husgafvel's  furnace  (Howe). 

C.  W.  Siemens'  process:  In  one  of  his  early  direct  processes 
two  cast-iron  retorts  or  hoppers,  with  fire-clay  ends,  were  sus- 
pended above  the  hearth  of  an  open  hearth  furnace.  Around 
each  hopper  is  a  space  heated  by  a  regulated  supply  of  flame  from 
the  open  hearth  furnace:  within  is  a  wrought-iron  pipe  supply- 
ing producer  gas  for  deoxidizing  the  ore.  About  28  pounds  of 
charcoal  is  charged  through  each  hopper,  and  on  this  sufficient  ore 
to  fill  the  hopper  completely.  Producer  gas  is  then  injected 
through  the  pipes  in  the  center  of  the  hoppers,  and  deoxidizes  the 
ore  which  has  meanwhile  been  raised  to  redness  by  the  heat  con- 
ducted through  the  walls  of  the  hoppers.  About  half  a  ton  of  pig 
iron  is  charged  on  the  open  hearth;  melting,  it  dissolves  the  lower 
end  of  the  columns  of  more  or  less  completely  deoxidized  iron, 
with  a  rapidity  which  is  only  limited  by  the  time  needed  to  deoxi- 
dize the  ore  in  the  hopper.  Sufficient  sponge  having  been  thus 
melted  off  in  three  or  four  hours,  charging  ceases,  the  remaining 
ore  in  the  hopper  sinks,  a  clay-coated  cast-iron  cover  suspended 
by  strong  wire  descending  with  the  ore  column,  so  that  the  flame 
may  not  enter  the  empty  hoppers.  On  this  cover  is  placed  the 
charcoal  and  ore  of  the  subsequent  charge,  eventually  lowered  by 
cutting  the  wire.  The  charge  already  melted  is  brought  to  the 
right  degree  of  carburization,  and,  after  an  addition  of  spiegel- 
eisen,  is  tapped  (Howe). 

In  the  later  process  (Siemens'  precipitation  process)  fine  ore 
was  reduced  by  coal,  with  which  it  was  mixed  and  heated  in  a 
rotating  furnace,  the  coal  precipitating  metallic  iron  from  the 
molten  ore.  The  resulting  metal  was  balled  as  in  puddling, 
squeezed  to  expel  slag,  and  either  used  as  material  for  the  open 
hearth  process,  or  worked  into  merchantable  wrought  iron.  The 
furnace  was  regenerative  and  gas  fired  (Howe). 

The  cascade  furnace,  used  at  one  time  by  Siemens,  instead  of  a 
rotator,  had  two  hearths  at  different  levels.  A  lake  of  fused  ore 
was  formed  on  the  upper  hearth,  and,  by  piercing  the  intervening 
bank  of  unmelted  ore,  was  run  at  intervals  upon  the  lower  hearth, 
upon  which  meanwhile  a  layer  of  equal  parts  of  powdered  anthra- 
cite or  coke  and  ore  had  been  spread.  On  stirring,  the  mass 
foamed  and  became  pasty;  in  from  40  to  50  minutes  the  iron, 
precipitated  by  the  carbon,  was  balled,  to  be  melted  in  the  open 
hearth  or  squeezed  (Howe). 

In  Frederick  Siemens'  process  ore,  coal,  and  fluxes  are  charged 
continuously  through  a  slit  at  the  end  of  a  regenerative  gas  fur- 
nace, which  is  rectangular  in  plan,  with  the  entrance  and  exit 
ports  at  the  same  end,  the  opposite  end  being  strongly  inclined. 
The  heat  is  so  high  that  the  ore  melts  immediately  on  entering 


DIRECT  PROCESSES  147 

the  furnace,  and  so  coats  over  and  protects  the  coal  from  the  ac- 
tion of  the  flame  of  the  furnace.  The  melting  ore  trickles  down 
the  incline,  its  iron  being  reduced  by  the  coal,  partly  during  its 
descent,  partly  after  reaching  the  bath  at  the  bottom  of  the 
incline.  Basic  additions  are  made  to  the  molten  slag  to  permit 
dephosphorization  and  the  reduction  of  the  iron.  The  slag  runs 
out  continuously;  the  metal  is  tapped  from  time  to  time  (Howe). 

In  Snelus*  process  the  ore,  heated  in  a  special  form  of  furnace, 
was  to  be  reduced  by  carbonic  oxide  or  hydrogen. 

O.  Stromborg's  process  employs  an  open  hearth  furnace  pro- 
vided at  the  top  with  special  reservoirs  from  which  tubes  extend 
down  below  the  surface  of  the  bath  on  the  hearth  through  which 
ore  and  carbon,  separately,  are  forced  under  air  pressure.  The 
furnace  being  provided  with  molten  steel,  carbon  is  introduced, 
and,  after  it  has  been  taken  up  by  the  bath,  ore  is  added  to  be 
reduced  by  the  carbon.  Heating  may  be  effected  by  producer 
gas  as  in  ordinary  open  hearth  practice,  but  principally  by  blowing 
air  through  one  of  the  feed  pipes.  A  limy  slag  is  employed  which 
can  be  tapped  off  as  necessary. 

The  stiickofen  or  old  high  bloomary  (also  called  salamander 
furnace,  wolf  furnace,  wolf  oven,  wulf 's  oven,  and  stuck  oven) 
was  a  shaft  furnace  10  to  16  feet  high,  either  round  or  rectangular 
in  section,  and  provided  with  one  tuyere,  somewhat  over  a  foot 
above  the  hearth,  and  a  drawing  hole  for  the  blooms.  It  may  be 
considered  as  approaching  the  present  blast  furnace,  and  fre- 
quently cast  iron  was  produced.  The  fuel  was  charcoal.  The 
wolf  oven  was  somewhat  lower,  and  between  it  and  the  stiickofen 
German  metallurgists  (Percy)  place  a  furnace  of  intermediate 
height  called  blaseofen  and  bauernofen  (osmund  furnace,  in 
Sweden).  The  product  of  the  stuctofen  may  contain  a  certain 
amount  of  highly  carburized  iron,  and  when  the  bloom  is  reheated 
and  most  of  this  cast  iron  runs  out,  the  remainder,  which  is  more 
infusible  (wrought  iron),  is  called  a  blume  (Overman). 

Swedish  Metallic  Sponge. — This  appears  to  be  manufactured 
by  a  process  similar  to  Chenot's.  It  is  obtained  by  reducing 
compressed  briquettes  of  ore  by  carbon  monoxide  at  a  tempera- 
ture slightly  below  the  melting  point  of  iron.  The  ore  used  is 
a  magnetite  as  pure  as  possible.  The  sponge  produced  is  very 
light,  in  color  varies  from  blue  to  black,  has  no  metallic  luster, 
and  is  not  very  pleasing  in  appearance.  The  analysis  of  a 
sample  showed  metallic  iron  slightly  over  96%  (Rev.  Met.). 

The  Tourangin  process  is  a  modification  of  Chenot's  direct 
or  internal  method  of  heating.  The  furnace  employed  was 
about  20  feet  high,  and  cost  less  than  Chenot's,  but  the  principle 
was  the  same.  The  sponge  produced  was  drawn  at  the  bottom, 
covered  with  ashes,  or  kept  in  special  water-jacketed  legs  at 
each  side  of  the  furnace  until  cool,  and  subsequently  worked  up 
in  a  charcoal  hearth,  etc.  (Percy). 

In  the  Trosca  process  ore  was  reduced  by  contact  with  carbo- 
naceous matter  in  externally  heated  vertical  retorts;  the  resulting 
sponge  was  removed  in  an  air-tight  buggy  (Howe). 

In  the  Twynam  process  briquettes  of  ore  and  carbonaceous 


148     DIRECT  RECOVERY— DODECAHEDRAL 

matter  were  thrown  into  the  bath  of  metal  in  a  basic  open 
hearth  furnace. 

Westman's  process  resembles  Cooper's  except  that  common 
producer  gas  is  used,  and  that  the  gas  passes  through  the  regenera- 
tor while  on  its  way  from  the  gas  producer  to  the  deoxidizing 
furnace  (Howe). 

In  the  Wilson  process  coarsely  pulverized  ore  with  20% 
of  charcoal  or  coke  dust  is  heated  to  800°  to  1000°  F.  (427°  to 
538°  C.)  for  24  hours  in  vertical  retorts  at  the  end  of  a  puddling 
furnace  by  whose  waste  heat  they  are  heated  externally.  The 
partially  deoxidized  ore  is  then  dropped  into  a  second  hearth  of 
the  puddling  furnace,  and  after  20  minutes  more  is  pushed  into 
the  hearth  proper  where  it  is  balled  (Howe). 

The  Yates  process  appears  to  be  identical  in  principle  with 
Chenot's  indirect  heating  process,  reduction  of  the  ore  being 
effected  by  heating  in  contact  with  carbonaceous  matter  in 
vertical  retorts  in  sections,  one  above  the  other,  connected  by 
socket  joints,  and  heated  externally  with  producer  gas.  The 
sponges  produced  are  balled  in  a  puddling  furnace. 

Direct  Recovery  Process. — See  page  96. 

Direct  Stress. — See  page  332. 

Dirt  Inclusion. — See  page  57. 

Dirt  Pocket. — See  page  311. 

Dirty  Gas.— See  page  33. 

Discard. — In  rolling  or  forging,  particularly  ingots,  the  portion  cut 
off  and  rejected  to  insure  sound  material.  The  discard  from  the 
top,  whether  from  the  ingot,  the  bloom  or  billet,  or  the  finished 
section,  containing  the  pipe  and  the  segregated  portion,  is  called 
specifically  the  top  discard,  and  the  piece  next  to  it,  the  top  cut ; 
the  discard  at  the  bottom,  the  bottom  discard,  and  the  piece  next 
to  it,  the  bottom  cut.  Both  discards  are  also  referred  to  as 
crops  or  crop  ends. 

Discontinuous  Combustion. — See  page  202. 

Discontinuous  Curve. — See  Curve. 

Discrystallization. — Amorphizing:  seepage  282. 

Dishing.— See  Cold- Working. 

Disk  Radio -balance. — See  page  207. 

Dissociation ;  Point ;  Theory. — See  page  89. 

Dissolved  Carbon. — See  page  275. 

Distillation. — See  page  202. 

Distillation  Process.— See  page  385. 

Distinct  Cleavage. — See  page  124. 

Distortion. — See  page  334. 

Distribution  of  Carbon. — See  page  213. 

Distribution,  Coefficient  of. — See  Coefficient  of  Distribution. 

Distributor. — For  ore:  see  page  32. 

Divalent. — See  page  86. 

Divariant  System.— See  page  327. 

Division. — See  page  81. 

Divorcing ;  Divorcing  Annealing. — See  page  274. 

Dode  Process.— See  page  370. 

Dodecahedral  Cleavage.— See  page  124. 


DODECAHEDRAL     IRON     ORE— DRAW     PLATE     149 

Dodecahedral  Iron  Ore. — See  page  244. 

Dog  Collar. — See  page  315. 

Dolite. — See  page  399. 

Dolly. — A  heavy  iron  bar,  suspended  at  about  the  middle,  used  to 
strike  a  heavy  blow  by  swinging  it  against  the  given  object 
in  the  same  manner  as  with  an  ancient  battering  ram;  also  called 
tup  or  monkey. 

Dolomite. — See  pages  175  and  397. 

Dominant  Element ;  Metal. — In  an  alloy:  see  page  4. 

Dormer  Mill. — See  page  434. 

Doubles. — Of  sheets:  see  page  430. 

Double-acting  Hammer. — See  page  196. 

Double  Annealing. — See  page  232. 

Double-burned  Dolomite. — See  page  397. 

Double  Furnace ;  Double-double  Furnace. — See  page  376. 

Double  Gross  Ton  (obs.).— See  Ton. 

Double  Hardening. — See  page  228. 

Double-level  Furnace. — See  page  312. 

Double -melting  Process. — See  page  75. 

Double  Mill. — See  page  430. 

Double  Pouring. — See  page  57. 

Double-refined  Iron. — See  page  378. 

Double-rolled  Iron. — See  page  378. 

Double  Shear. — See  page  337. 

Double  Shear  Heat. — See  page  71. 

Double  Shear  Steel.— See  Shear  Steel. 

Double  Shrink. — See  page  296. 

Double  Skip. — See  page  33. 

Double  Steel;  Doubler ;  Doubling  Shear. — Of  sheets:  see  page  430. 

Doubly  Converted  Bars. — See  page  71. 

Doubly  Oblique  System. — Of  crystallization:  see  page  120. 

Doubly  Refined  Iron. — See  page  378. 

Dowlais  Mill. — See  page  417. 

Down  Draft  Producer. — See  Producer. 

Downcomer. — See  page  33. 

Dowson  Gas. — See  Producer. 

Dozzle. — See  page  59. 

Draft. — (i)  In  molding:  see  page  296;  (2)  in  rolling:  see  page  407. 

Draft  Fluid  Compression. — See  page  64. 

Drag. — See  page  297. 

Draper's  Law. — See  page  208. 

Draught.— See  Draft. 

Draw. — (i)  In  the  crucible  process:  see  page  115;  (2)  in  heat 
treatment:  see  pages  230  and  2325^(3)  in  molding:  seepage  296; 
(4)  of  wire:  see  page  507. 

Draw  Bench. — See  page  508. 

Draw  Bottom. — See  page  17. 

Draw  Down. — To  reduce  the  section  of  a  piece  of  metal  by  mechan- 
ical means,  such  as  hammering,  rolling,  or  drawing. 

Draw  Hole. — (i)  In  castings:  see  page  53;  (2)  for  wire:  see  page 
507- 

Draw  Plate.— See  page  507. 


1 50  DRAW  TEMPERING— DUCTILIMETER 

Draw  Tempering. — See  pages  230  and  232. 

Drawing  Back. — See  pages  230  and  232. 

Dressing. — (i)  Of  castings:  see  page  58;  (2)  of  ores,  preparing  by 

crushing,  washing,  etc.  (but  not  roasting) ;  (3)  of  metallic  pieces, 

machining;  (4)  of  rolls,  turning  down  in  a  lathe  after  they  have 

become  worn. 

Drier. — Of  a  paint:  see  page  365. 
Drift  Test.— See  page  477. 
Drill  Temper. — See  Temper. 

Driving-in  Method. — To  determine  hardness:  see  page  478. 
Drop  (obs.)  —  See  Slag. 
Drop  of  the  Bath. — See  page  376. 
Drop  of  the  Beam. — See  page  469. 
Drop  Bottom. — See  page  182. 
Drop  of  the  Flame. — See  page  20. 
Drop  Forging. — See  Forging. 
Drop  Hammer. — See  page  197. 
Drop  Stamping  (Eng.). — Drop  forging. 
Drop  Test ;  Drop  Weight  Test. — See  page  481. 
Dross. — The  sullage,  scurf,  oxide,  or  other  impurities  which  are 

skinned  off  the  top  of  molten  metals,  or  which  accumulate  in  the 

sinkhead  or  riser  of  a  casting. 

Drummer  (Eng.). — A  smith's  hammerman  (Homer).  r  v 

Druse;  Drusy  Cavity. — See  page  125. 
Dry  ;  Dryness. — (i)  Of  pig  iron,  low  in  silicon;  (2)  of  slags,  infusible; 

(3)  of  steel  which  is  red-short  or  tender:  see  Brittleness. 
Dry  Analysis. — See  page  82. 
Dry  Blacking. — See  page  298. 
Dry  Blast. — See  page  29. 
Dry  Bottom. — See  pages  253  and  377. 
Dry  Brush.— See  page  298. 
Dry  Cleaning.— Of  gas:  see  page  33. 
Dry  Coal.— See  Coal. 
Dry  Drawing. — Of  wire :  see  page  508. 
Dry  Dust  Catcher. — See  page  33. 
Dry  Finish. — Of  sheets:  see  page  433. 
Dry  Fusion. — See  page  201. 
Dry  Galvanizing. — See  page  371. 
Dry  House.^-In  wire  practice:  see  page  507. 
Dry  Iron. — See  page  343. 
Dry  Method  of  Analysis. — See  page  82. 
Dry  Ore  (Eng.).— See  page  243. 
Dry  Process. — See  page  82. 
Dry  Puddling. — See  page  374. 
Dry  Sand ;  Dry  Sand  Molding. — See  page  296. 
Dry  Slag.— See  Slag. 
Drying. — (i)  Of  molds:  see  page  298;  (2)  same  as  coming  to  nature: 

see  page  376. 

Drying  Oven ;  Stove. — See  page  298. 
Du  Puy  Process. — See  page  140. 
Dualistic  Theory. — See  page  89. 
Ductilimeter  (rare). — See  page  483. 


DUCTILITY— DYNAMOMETER  151 

Ductility.— (i)  General:  see  page  331 ;  (2)  formulae  for:  see  page  338. 

Ductility  test.— See  pages  481  and  483. 

Diidelingen  Process. — See  Recarburization. 

Dull  Fracture. — See  page  178. 

Dull  Iron  ;  Metal.— See  page  343. 

Dulong's  Law. — See  page  203. 

Dulong  &  Petit's  Law. — See  page  85. 

Dummy  Tuyere. — See  page  17. 

Dump. — To  discharge  by  gravity,  as  the  contents  of  a  cupola. 

Duo  Mill. — See  page  408. 

Duplex  Constituent. — Eutectic:  see  page  266. 

Duplex  Process. — See  page  317. 

Durr  (Eng.). — Jar  or  shock. 

Dust  Catcher  ;  Chamber. — (i)  In  connection  with  a  blast  furnace: 

see  page  33;  (2)  this  term  is  rarely  used  for  the  cinder  pocket  of 

an  open  hearth  furnace. 
Dust  Coke. — See  page  97. 
Dust  Plate  (obs.). — A  vertical  iron  plate  supporting  the  slag  runner 

of  a  blast  furnace  (Raymond). 
Dusting. — Of  sheets:  see  page  430. 
Dwight  and  Lloyd  Process. — See  page  45. 
Dyad.— See  page  86. 
Dyer  Process. — See  page  317. 
Dynamic  Deformation. — See  page  333. 
Dynamic  Hardness. — See  page  331. 

Dynamic  Indentation. — To  determine  hardness:  see  page  478. 
Dynamic  Load. — See  page  333. 
Dynamic  Metamorphism. — See  page  122. 
Dynamic  Methods. — Of  hardening:  see  page  279. 
Dynamic  Resistance ;  Strains ;  Strength ;  Stress. — See  pages  330  and 

333- 

Dynamic  Test. — See  pages  468  and  481. 
Dynamic  Theory  of  Heat. — See  page  199. 
Dynamometer. — See  page  483. 


E 

Er. — Chemical  symbol  for  erbium:  see  page  84. 

Eu. — Chemical  symbol  for  europium:  see  page  84. 

E.B.B.  Wire. — See  page  509. 

E.S.C.  (Brit.)- — The  Engineering  Standards  Committee  (q.v.). 

Eames  Process. — See  page  138. 

Ease,  State  of. — See  page  332. 

East  Coast  Hematite. — See  page  344. 

Eaton  Process. — (i)  In  cementation:  see  page  68;  (2)  in  purifica- 
tion: see  page  385. 

Ebullition. — See  page  202. 

Eccentric  Converter. — See  page  17. 

Edge  Steel. — In  a  casting,  the  metal  solidifying  first  on  the  outside, 
and  which  on  etching  sometimes  presents  a  different  appearance 
from  the  central  portion  which  is  then  called  core  steel. 

Edging  Pass. — See  page  408. 

Edison  Gage. — See  page  187. 

Edwards  and  Carpenter's  Theory. — Of  hardening:  see  page  381. 

Edwards  Flying  Shears. — See  page  413. 

Efficiency  of  Corrosion. — See  page  108. 

Effloresce;  Efflorescence. — See  Water. 

Egg  Coke.— See  page  97. 

Ehrenwerth  Process. — See  page  141. 

Ehrenwerth  and  Prochaska  Process. — See  page  317. 

Eifel  Walloon  Process. — See  page  80. 

Eisen-Portland. — See  Slag  Cement. 

Elastic  After-working.— See  page  333. 

Elastic  Break- down.— See  page  333. 

Elastic  Compressive  Strength. — See  page  336. 

Elastic  Deformation. — See  page  330. 

Elastic  Limit. — (i)  General:  see  pages  330  and  469;  (2)  by  dividers: 
see  page  470;  (3)  by  drop  of  the  beam:  see  page  470;  (4)  by  exten- 
someter:  see  page  470. 

Elastic  Limit  Strength. — See  page  330. 

Elastic  Ratio. — See  page  335. 

Elastic  Resilience  ;  Strain ;  Strength. — See  pages  330  and  331. 

Elasticity. — (i)  General:  see  page  330;  (2)  coefficient  of:  see  page 
334;  (3)  modulus  of:  see  page  334. 

Eldred  Process. — See  page  24. 

Electric  Arc  Furnace.— See  page  153. 

Electric  Arc-resistance  Furnace.— See  page  153. 

Electric  Blast. — See  page  503. 

Electric  Casting. — See  page  65. 

Electric  Furnace  Process.— See  page  153. 

Electric  Furnaces,  Types  of.— See  page  153. 

Electric  Hardening.— See  page  230. 

Electric  Processes. — For  cementing:  see  page  70. 

Electric  Processes. — Electricity,  in  the  commercial  manufacture  of 

152 


ELECTRIC  PROCESSES  153 

iron  and  steel,  is  used  almost  exclusively  as  a  source  of  the  heat 
necessary  to  cause  the  various  reactions  to  take  place,  and  not  for 
any  direct  chemical  action,  or  only  to  a  limited  and  practically 
negligible  extent;  the  more  correct,  and  therefore  preferable, 
designation  is  electro-thermal  or  electro -thermic  process  or,  re- 
ferring to  the  type  of  furnace  employed,  electric  furnace  process 
(also  termed  electro -metallurgical  process,  and  the  product,  elec- 
tric steel).  Electrolysis  of  suitable  solutions,  which  depends  on  a 
direct  chemical  reaction,  has  recently  been  developed  to  a  point 
where  production  of  nearly  pure  iron  is  on  a  commercial  but 
comparatively  limited  scale  (see  Electrolytic  Iron,  page  165). 

Electro-thermic  processes  may  be  classified  according  to  the 
following  types  of  furnace,  based  on  the  manner  in  which  the 
heating  is  effected. 

1.  Induction  furnace  (induction  heating) :  The  furnace  usu- 
ally consists  of  an  annular  trough  (the  furnace  proper),  the  con- 
tained metal  constituting  part  or  all  of  the  secondary  circuit  of  a 
transformer  (an  alternating  current  must  be  employed),  the  pri- 
mary circuit  of  which  is  arranged  as  usual.     The  type  where  the 
bath  forms  the  entire  secondary  winding  is  called  a  simple  induc- 
tion furnace ;  where  the  bath  forms  only  a  part  of  the  secondary 
circuit,  a  copper  winding  being  added  to  assist  in  the  heating,  it 
is  a  combination  induction  furnace. 

2.  Resistance  furnace   (resistance  heating):  The  charge  or 
bath  of  metal  forms  part  of  the  regular  circuit,  and  the  resist- 
ance it  offers  to  the  passage  of  the  current  yields  the  required 
temperature. 

3.  Surf  ace  resistance  furnace :  The  electrodes  do  not  suffice  for 
the  passage  of  the  current.     To  heat  up  the  furnace  it  is  necessary 
to  connect  them  by  means  of  some  kind  of  conducting  material, 
such  as  a  bed  composed  of  pieces  of  carbon.     These  conductors 
are  then  brought  to  a  state  of  extreme  incandescence,  and  form  a 
melting  hearth  upon  which  the  materials  to  be  treated  are  placed. 
The  materials  themselves  afterward,  being  traversed  throughout 
their  extent  by  the  current,  serve  as  a  conductor  between  the 
electrodes  (Keller). 

Arc  furnace,  radiation  furnace,  or  arc  radiation  furnace  (arc 
heating,  radiation  heating) :  The  requisite  temperature  is 
obtained  by  radiation  from  an  arc  (radiating  arc)  formed  between 
two  electrodes,  or  between  two  or  more  electrodes  and  the  charge. 
In  the  latter  case  the  current  may  pass  from  one  electrode  into  the 
bath,  then  out  again  to  another  electrode  in  series  with  the  first, 
or  through  the  bottom  of  the  furnace  (which  in  this  case  forms  an 
electrode) ;  the  direction  being  constantly  reversed  if  an  alternat- 
ing current  is  employed.  By  either  method  a  certain  amount  of 
resistance  heating  occurs  (indirect  resistance  heating),  and  this 
combination  is  called  an  arc-resistance,  resistance -arc,  or 
combined  arc  and  resistance  furnace. 

The  advantages  of  electric  heating  as  compared  with  that 
obtained  from  the  combustion  of  fuel  are,  in  general: 
(a)  A  higher  temperature  available. 


154  ELECTRIC  PROCESSES 

(b)  The  possibility  for  greater  purification,  both  because  the 

high  temperature  available  permits  a  slag  high  in  lime 
which  otherwise  would  be  too  infusible,  and  also  because 
reducing  conditions  can  be  maintained  (particularly  at 
the  end  of  the  process)  whereby  reduction  and  consequent 
elimination  of  oxides  and  dissolved  oxygen  can  be 
secured. 

(c)  More  complete  exclusion  of  air  or  gases  (except  in  the 

case  of  the  crucible  process). 

(d)  Carbon  is  required  only  for  reduction  (also  for  recar- 
burization,  if  desired) ,  including  what  is  added  to  the  slag 
for  this  purpose,  hence  a  smaller  amount  of  impurities  is 
introduced  than  with  ordinary  fuel. 

The  usual  disadvantage  is: 

(e\  That  the  cost  is  generally  higher,  except  where  power  is 
extremely  cheap  and  fuel  dear  (as  in  Norway),  so  it  is 
usually  available  only  for  the  finer  grades  of  steel  (e.g.,  to 
replace  that  made  by  the  crucible  process),  or  when  used 
simply  for  final  purification. 

The  furnaces  are  nearly  always  basic  lined,  so  that  purification 
with  lime  can  be  effected,  but  they  can  also  be  acid  lined  if  desired. 

Allevard  process:  Very  little  has  been  published  about  this 
process.  It  is  stated  that  an  electrode  furnace  is  employed  in 
which  various  grades  of  steel  are  made  from  either  pig  and  ore  or 
pig  and  scrap. 

The  Anderson  furnace  for  refining  or  making  steel  appears 
to  be  very  similar  to  a.Heroult  furnace,  with  the  addition  of 
electro-magnets  placed  underneath  the  furnace  in  line  with  the 
electrodes,  from  which  arrangement  benefits  are  claimed.  A 
type  for  smelting  ores  is  similar  to  the  Keller  furnace,  designed 
for  that  purpose. 

The  Bailey  resistance  furnace  is  used-simply  as  a  heating  furnace 
for  forging  or  heat  treating  purposes.  The  resistance  material  is 
essentially  crushed  coke  connected  with  graphite  electrodes  and 
protected  by  a  lining  of  magnesite. 

The  Borchers  furnace,  which  is  somewhat  similar  to  the  above, 
being  used  only  for  heating  purposes,  employs  a  carbon  rod  of 
relatively  small  cross-section,  called  a  resistor,  which  is  heated 
by  the  passage  of  the  current,  and  about  which  the  charge  is 
placed. 

The  Burke  furnace  is  of  the  arc  type,  operates  at  perferably  two 
phase,  each  circuit  entirely  distinct  from  the  other  (Vom  Baur). 

In  the  Chapelet  furnace,  of  the  arc  type,  the  current  flows  into 
the  bath  from  a  hanging  carbon  electrode,  much  as  in  the  Girod 
furnace.  From  the  bath  it  goes  through  a  horizontal  channel  to 
a  hanging  cast  iron  electrode  that  touches  the  channel.  This 
constitutes  the  peculiarity  of  the  furnace.  It  is  not  apparent 
that  this  offers  any  advantage  over  the  Girod  arrangement  (Vom 
Baur). 

The  Colby  furnace  is  very  similar  to  the  Kjellin,  differing 
principally  in  the  use  of  a  copper  tube,  through  which  water 


ELECTRIC  PROCESSES  1 5  5 

circulates,  for  the  primary  coil.  It  was  patented  by  E.  A.  Colby, 
and  the  rights  for  these  two  furnaces  in  this  country  have  bee'n 
consolidated  under  one  management;  it  is  then  called  a  Kjellin- 
Colby  furnace. 

M.  R.  Conley's  process  is  somewhat  similar  to  Stassano's, 
as  reduction  and  purification  are  effected  in  the  same  chamber. 
The  furnace  employed  has  somewhat  the  shape  of  a  blast  furnace : 
the  walls  converge  at  about  the  middle,  below  which  is  the  hearth 
where  the  final  reduction  and  melting  take  place;  the  charge  is 
introduced  at  the  top,  and  the  molten  products  are  tapped  out 
through  a  hole  at  the  bottom.  The  furnace  is  of  the  resistance 
type:  the  current  is  brought  into  contact  with  the  charge  by 
means  of  two  graphite  electrode  rings  built  into  the  wall,  one  of 
which  is  at  the  narrowest  point  of  the  furnace  and  the  other  a 
short  distance  above.  It  was  designed  to  produce  either  cast 
iron  or  steel. 

The  Crafts  furnace  is  a  steel  furnace  of  the  induction  type 
in  which  the  transformer  cores  are  horizontal  instead  of  vertical. 
These  cores  are  around  heating  channels  leading  up  to  the  bath 
above,  much  like  the  flues  in  an  open  hearth  furnace.  The 
channels  are  always  full  of  molten  metal.  The  bath  can  be 
worked  as  in  an  open  hearth  furnace  (Iron  Age,  Sept.  18,  1913). 

In  the  Ferranti  process,  patented  in  1885,  the  first  induction 
furnace  was  employed,  which,  however,  did  not  prove  a  com- 
mercial success.  It  consisted  of  a  laminated  iron  core  wound 
with  fine  wire,  constituting  the  primary  circuit,  and  around 
this  an  annular  refractoryitrough  in  which  the  molten  metal  formed 
the  secondary  circuit. 

The  Frick  furnace  is  of  the  induction  type,  and  is  very  similar 
to  the  Kjellin,  the  principal  difference  being  that  in  the  former 
the  primary  windings  are  placed  above  and  below  the  annular 
hearth  instead  of  within  it.  Heating  is  produced  in  exactly 
the  same  way.  Another  difference  is  that  the  Frick  furnace 
has  a  single  cover  which  can  be  rotated,  so  that,  by  having 
one  opening,  the  whole  of  the  ring-shaped  hearth  can  be  in- 
spected. Also  a  skimmer  introduced  through  the  hole  during 
rotation  would  serve  to  bring  the  slag  to  the  spout  very  easily. 

The  Galbraith  furnace  was  designed  to  extract  iron  from 
fine  ores  without  previous  briquetting.  The  iron  sand  is  mixed 
with  fine  carbon  and  is  led  downward  in  a  zigzag  manner  in  a 
furnace  constructed  entirely  of  graphite  over  twelve  roasting 
bars  also  made  of  graphite.  The  entire  furnace  is  closed.  On 
their  way  through  the  furnace,  the  ores  mixed  with  fine  carbon 
are  reduced  and,  to  assist  in  this,  carbureted  hydrogen  is  also 
introduced  into  the  lower  portion  of  the  furnace.  The  iron  col- 
lects at  the  bottom  in  a  liquid  state. 

Gin  furnace :  One  form  is  of  the  resistance  type.  In  this  the 
metal  is  contained  in  a  long,  narrow,  shallow  trough  to  obtain 
sufficient  resistance  and  which,  for  convenience,  is  doubled  upon 
itself.  Connection  with  the  current  is  made  at  the  ends  of  the 
trough  by  two  water-cooled  metal  electrodes  plunged  in  the 
molten  metal.  A  later  form  is  of  the  induction  type:  the  metal 


156 


ELECTRIC  PROCESSES 


circulates  in  a  number  of  troughs  connected  together  by  channels; 
the  bottoms  of  the  troughs  are  inclined.  The  furnace  is  tilting, 
and  has  a  rectangular  shape. 

The  Girod  furnace  resembles  a  small  tilting  open  hearth 
furnace.  The  hearth  consists  of  a  circular  or  oblong  cavity 
in  which  the  metal  when  molten  reaches  a  height  of  from  10 
to  ii  inches.  One  or  more  electrodes  (depending  upon  the 
size  of  the  furnace)  in  parallel  are  maintained  above  the  bath, 
and  soft  steel  pieces,  embedded  in  the  hearth  of  the  furnace, 
and  in  direct  contact  with  the  molten  metal,  form  the  negative 


FIG.   16. — Girod  furnace. — A,  molten  metal.     B,  upper  electrode. 
C,  lower  electrode  (Eng.  and  Min.  Jour.). 

electrode.  The  current,  entering  by  the  way  of  the  upper  elec- 
trode, forms  an  arc  between  itself  and  the  bath,  traverses  the 
bath,  and  passes  out  through  the  lower  pole  pieces,  the  upper 
parts  of  the  lower  pole  pieces,  which  are  in  direct  contact  with 
the  metallic  bath  become  molten  at  their  extreme  ends;  the 
lower  ends  are  water-cooled.  This  furnace  is  of  the  arc  type. 
Giron  also  manufactured  ferro-alloys  in  a  resistance  furnace  in 
which  the  resistance  consisted  of  a  layer  of  graphite  in  the  walls; 
this  type  was  also  used  for  a  crucible  furnace. 

The  Grondal-KjelHn  furnace,  or  Grondal  furnace,  is  a  modi- 
fication of  the  original   Kjellin  furnace,   differing  principally 


ELECTRIC  PROCESSES 


in  the  method  of  forming  the  primary  circuit,  and  in  means 
provided  for  tilting. 

The  Gronwall  furnace  of  the  induction  type  was  devised  with 
the  object  of  increasing  the  resistance  of  the  bath  and  so  improve 
the  power  factor  by  greatly  elongating  the  ordinary  channel  of 


FIG.   17. — Gronwall  furnace;  vertical  section. 

the  induction  furnace.     This  result  is  largely  secured,  but  with 
considerable  losses  of  heat  by  radiation  (Vom  Baur). 

The  Gronwall  or  Gronwall,  Lindblad  and  Staalhane  electric 
shaft  furnace  is  devised  for  the  reduction  of  iron  from  its  ore,  and  is 
unlike  any  hitherto  constructed,  resembling  most  nearly  an  ordi- 
nary blast  furnace  in  which  the  tuyeres  are  replaced  by  electrodes, 


158  ELECTRIC  PROCESSES 

three  in  number.  The  height  of  the  furnace  above  ground  level  is 
about  25  feet.  The  melting  chamber  or  crucible  containing  the 
electrodes  is  about  7  feet  high,  and  is  of  greater  diameter  than  any 
other  part.  The  shaft  is  about  18  feet  high,  the  lower  end  of 
which — for  about  4  feet — has  the  form  of  an  inverted  truncated 
cone;  the  angle  of  this  cone  is  for  the  purpose  of  directing  the 
charge  into  the  crucible  in  such  a  manner  that  the  electrodes,  lin- 
ing, and  descending  charge  could  not  come  into  contact.  The 
melting  chamber  is  made  in  the  form  of  a  crucible,  and  is  covered 
with  an  arched  roof  provided  with  openings  for  the  reception  of 
the  electrodes  and  for  the  descending  charge.  The  roof  and 
walls  of  the  crucible  are  lined  with  magnesite.  For  the  purpose  of 
cooling  the  brick- work  composing  the  lining  of  the  roof  of  the  melt- 
ing chamber,  and  thereby  increasing  its  life,  three  tuyeres  are 
introduced  into  the  crucible-j-just  above  the  melting  zone — 
through  which  the  comparatively  cool  tunnel-head  gases  are 
forced  against  the  lining  of  the  roof  into  the  free  spaces.  The 
shaft  is  supported  independently  above  the  melting  chamber  by 
an  iron  plate  resting  on  six  cast-iron  pillars.  The  charge,  con- 
sisting of  ore,  coke  (or  charcoal),  and  limestone,  is  introduced  at 
the  top  by  means  of  a  bell  and  hopper,  and  the  molten  products 
are  tapped  out  through  a  hole  at  the  bottom  of  the  hearth. 

The  Halberger  furnace  is  of  the  indirect  resistance  type  for 
crucible  melting  and  is  arranged  so  the  resistance  is  furnished  by 
the  walls  of  the  crucibles  themselves,  which  are  made  of  the  ordi- 
nary carbon  or  graphite  mixtures.  Before  using  they  are  pre- 
pared by  a  patented  process  which  permits  the  current  to  pass 
through  the  crucible  walls  only  (Vom  Baur). 

The  Harmet  process  was  devised  for  the  production  of  iron  and 
steel  direct  from  the  ore,  and  does  not  differ  materially  from  vari- 
ous others.  The  furnace  consists  of  three  superimposed  fur- 
naces connected  together.  The  top  one  acts  as  a  calciner,  the 
middle  one  as  a  blast  furnace  for  the  reduction,  and  the  bottom 
one,  which  is  of  the  open  hearth  type,  for  the  refining  of  the  raw 
product.  Ore  and  flux  are  charged  into  the  calciner,  and  are 
heated  by  the  combustion  of  the  gases  resulting  from  the  reduc- 
tion of  the  ore  with  fuel  below. 

The  Helf enstein  furnace  is  of  the  shaft  type  and  was  originally 
used  for  the  manufacture  of  calcium  carbide  and  ferro-silicon,  but 
now  also  employed  for  making  pig  iron  and  steel.  There  may  be 
a  number  of  shafts  with  a  common  hearth  of  conducting  material. 
The  charge  is  introduced  continuously  at  the  top  of  the  shafts 
where  the  electrodes  are  located. 

The  HerSus  furnace  is  a  small  laboratory  furnace  for  heating 
crucibles,  combustion  tubes,  etc.,  consisting  of  a  tube  of  porcelain 
or  other  refractory  material  which  is  heated  by  a  resistance  coil  of 
platinum  wire  or  strip  wound  about  it,  and  protected  from  radia- 
tion on  the  outside  by  a  layer  of  heat  insulating  material. 

The  Hering  furnace  is  based  on  the  pinch  phenomenon :  When 
a  current  passes  through  a  conductor,  the  magnetism  produced 
in  and  about  it  has  a  crushing  effect,  as  the  surrounding  magnetic 
flux  acts  like  stretched  rubber  bands.  This  crushing  force  is  not 


ELECTRIC-PROCESSES 


159 


strong  enough  to  be  noticeable  in  solid  conductors,  but  when  they 
are  liquid,  and  the  current  is  sufficiently  large,  it  is  clearly  evident. 
This  is  sometimes  powerful  enough  to  sever  the  conductor,  and 
generally  occurs  locally  at  the  weak  spot.  If  the  conductor  con- 
sists of  a  column  of  molten  metal  confined  in  a  hole  in  a  refractory 
material  near  the  bottom  of  a  crucible,  and  if  the  outer  end  is 
sealed  by  the  electrode  and  the  inner  end  opens  into  the  bath  or 
in  the  crucible,  the  pinching  effect  will  force  the  liquid  out  through 
the  center  of  the  open  end.  As  this  end  is  submerged  the  con- 
ductor cannot  pinch  off,  but  instead  liquid  will  be  sucked  in  cir- 
cumferentially,  thus  producing  simultaneous  outward  and  inward 
flow  of  liquid  through  the  hole  (Hering,  Trans.  Am.  Electrochem. 
Soc.,  XXXV). 

The  Heroult  furnace  is  tilting,  and  is  very  similar  to  the  type 
employed  in  the  open  hearth  process  except  there  are  no  ports 
for  the  entrance  and  exit  of  gases.  There  are  usually  two  elec- 


FIG.  1 8. — Heroult  double  arc  furnace.     (Eng.  and  Min.  Jour.) 

trodes  which  pass  through  the  roof  and  whose  height  can  be 
regulated  by  suitable  means.  One  of  these  is  attached  to  the 
negative  pole  and  the  other  to  the  positive  pole,  and  the  current 
passes  between  them  through  the  bath  with  which  they  may  be 
in  contact,  but  are  generally  separated  by  a  small  space  over 
which  an  arc  is  maintained.  The  furnace  may  be  used  for  treat- 
ing materials  in  the  same  manner  as  in  the  open  hearth  process, 
but  it  has  been  found  advantageous  to  work  with  blown  metal 
from  a  Bessemer  converter,  or  nearly  finished  metal  from  an 
open  hearth  furnace.  The  purification  may  be  very  complete 
as  a  high-lime  slag  can  be  maintained.  As  a  rule  the  first 
slag,  containing  most  of  the  phosphorus,  is  removed,  and  a 
second  slag,  consisting  of  lime  and  fluorspar,  is  then  formed. 
Crushed  coke  is  added  to  complete  the  removal  of  the  oxygen  in 
the  bath.  A  process  devised  by  Ernest  Humbert  (Dr.  He*roult's 
metallurgist)  consists  in  removing  the  phosphorus,  not  as  usual  as 
phosphate  but  as  phosphide.  Use  is  made  of  an  oxidizing  basic 
slag  to  combine  with  the  phosphorus  and  form  a  phosphate,  after 
which  a  reducing  material,  usually  crushed  coke,  is  added,  and 


160  ELECTRIC  PROCESSES 

floats  on  the  slag,  reducing  the  calcium  phosphate  to  phosphide, 
which  cannot  be  taken  up  by  the  iron  as  phosphorus  without  first 
being  converted  back  to  phosphate.  In  this  way  it  is  intended  to 
purify  with  a  single  slag,  but  so  far,  on  tapping,  a  considerable 
amount  of  phosphorus  seems  to  pass  back  into  the  metal. 

Heroult  ore  smelting  furnace:  The  furnace  consists  of  an 
approximately  vertical  shaft  at  the  top  of  which  the  coke  for  the 
reduction  is  charged.  On  one  side  there  is  an  inclined  shaft  by 
which  the  ore  is  introduced  into  the  main  shaft  and  comes  into 
contact  with  the  column  of  coke.  The  heat  is  supplied  by  the 
resistance  of  the  charge  to  the  passage  of  the  current.  There  are 
two  electrodes,  both  consisting  of  solid  blocks  of  carbon,  one  of 
which  is  situated  near  the  top  of  the  coke  column,  and  the  other 
at  the  bottom  of  the  hearth.  The  action  is  somewhat  similar  to 
what  takes  place  in  a  blast  furnace,  the  molten  pig  and  slag  which 
collect  in  the  hearth  being  tapped  out  through  suitable  openings. 
A  modification  consists  of  a  single  shaft  with  a  tapping  hole  at  the 
bottom,  charcoal  being  used  for  fuel.  The  two  electrodes  consist 
of  a  carbon  block  in  the  hearth  and  a  large  carbon  rod  suspended 
at  the  top  of  the  shaft,  much  as  in  a  Keller  furnace. 

Hiorth  furnace:  The  leading  feature  of  this  furnace  is  that 
it  dispenses  with  the  use  of  electrodes.  A  large  electro-magnet,  in 
the  form  of  a  horseshoe,  has  across  the  two  ends  a  perpendicular 
rod,  about  which  it  can  move  readily.  Around  this  rod  is  the 
primary  winding  of  fine  wire.  Through  the  open  space,  and  sur- 
rounding the  top  of  the  horseshoe,  is  a  circular  trough  which  con- 
stitutes the  furnace  proper.  When  this  is  charged,  a  high  tension 
current  is  passed  through  the  windings  which  induces  a  secondary 
current  in  the  trough  and  its  contents. 

The  Irving  or  Moffat  furnace  consists  of  a  crucible  into  which 
three  inclined  electrodes  project,  where  reduction  is  completed 
with  coke,  surmounted  by  a  stack,  through  which  the  charge 
passes  to  the  crucible,  being  there  preheated  and  partially  re- 
duced by  carbon  monoxide. 

Keller  furnace  (Keller-Leleux  process) :  The  furnace  formerly 
employed  was  very  similar  to  the  H6roult  type,  the  current  pass- 
ing from  one  electrode  into  the  bath,  and  then  out  of  it  into  an- 
other electrode,  both  electrodes  being  above  the  bath.  In  one 
form  it  consisted  of  two  furnaces  at  different  levels,  one  fixed  and 
one  tilting.  When  working  with  pig  and  scrap,  the  materials 
were  melted  and  partially  refined  in  the  upper  stationary  furnace, 
and  then  run  into  the  lower  tilting  furnace  where  the  process  was 
completed;  with  scrap  alone  the  whole  operation  was  conducted  in 
the  tilting  furnace.  In  the  latest  type  adopted,  which  resembles 
Girod's  furnace,  there  is  only  one  electrode  at  the  top  or,  if 
several  electrodes  are  employed,  they  are  all  connected  in  parallel; 
the  other  terminal  is  the  bottom  or  hearth  of  the  furnace.  The 
current,  therefore,  passes  from  the  electrode  at  the  top  into  the 
bath  and  leaves  the  furnace  at  the  bottom.  In  a  recent  patent, 
which  provides  for  a  durable  bottom,  Keller  places  a  bundle  of 
iron  bars  vertically  in  the  furnace  bottom,  connecting  them  to  a 
conducting  plate  arranged  below  their  bottom  ends.  Between 


ELECTRIC  PROCESSES 


161 


these  bars  and  around  the  bundle  which  they  form,  a  refractory 
material,  preferably  magnesia,  is  strongly  rammed.  The  fur- 
nace bottom  consists,  therefore,  partly  of  vertical  iron  rods  and 
parly  of  magnesia,  the  latter  also  becoming  a  conductor  at  high 
temperatures. 

The  Keller  ore  smelting  furnace  is  practically  the  same  in 
principle  and  construction  as  the  form  originally'  employed  for 
making  steel,  and  is  of  the  resistance  type.  There  are  two  verti- 
cal shafts  connected  at  the  bottom  by  a  horizontal  canal.  The 
charge,  consisting  of  the  proper  proportion  of  ore,  coke,  and  flux, 
is  charged  at  the  top  of  both  shafts,  and  reduction  takes  place 
during  its  descent.  One  large  carbon  electrode  is  suspended  in 
each  shaft,  connected  respectively  to  the  negative  and  the  posi- 
tive terminals.  The  bottoms  of  the  shafts  are  connected  by  a 
copper  rod  on  the  outside  and  underneath,  fastened  to  blocks  of 
carbon.  A  small  well  between  the  two  shafts  serves  to  collect  the 
molten  materials.  If  there  is  any  danger  of  chilling  up,  a  third 
electrode  can  be  brought  into  action  at  this  point  to  supply  the 
additional  heat  required. 

The  Kjellin  furnace  is  of  the  induction  type.  The  hearth  or 
crucible  is  in  the  form  of  an  annular  ring  provided  with  covers, 


PIG.  19. — Kjellin  induction  furnace. — AA,  circular  trough  in 
which  steel  is  melted  and  treated.  C,  magnetic  core.  D,  primary 
coil.  E,  frame  connecting  ends  of  C.  F,  cover  for  melting  chamber. 
G,  spout.  (Eng.  and  Min.  Jour.} 

and  the  contained  metal  forms  the  secondary  circuit  of  a  trans- 
former, the  primary  circuit  of  which  consists  of  a  coil  of  fine,  in- 
sulated copper  wire  with  a  laminated  iron  core.  The  winding  is 
placed  on  one  leg  only,  the  primary  being  next  the  core,  and  the 
secondary  outside  of  this.  It  is  protected  from  radiated  heat  by 
air  spaces  and  a  water  jacket.  The  process  has  generally  been 
used  for  obtaining  steel  of  any  grade  from  dead  soft  to  hard  by  a 
suitable  mixture  o'f  pure  pig  and  scrap,  with  the  proper  additions 
of  ferro-silicon,  etc.;  little  purification  has  been  attempted.  The 
initial  charge  has  been  cold  pig  and  scrap,  but  after  it  has  been 
operating,  only  a  portion  is  tapped  out  each  time. 

The  Lavol  furnace  was  one  of  the  earlier  forms  of  resistance  fur- 
nace designed  for  refining  spongy  iron.     The  furnace,  of  cylindri- 
11 


l62 


ELECTRIC  PROCESSES 


cal  shape,  consisted  of  two  compartments  to  be  filled  with  molten 
iron  oxide  to  above  the  top  of  the  separating  wall.  The  current 
passed  through  this  between  electrodes  placed  in  the  bottom  of 
the  compartments.  The  spongy  iron  was  to  be  refined  while  sink- 
ing through  this  molten  oxide. 

The  Ludlum  furnace,  used  for  producing  cast  steel,  cast  iron, 
low  phosphorus  pig,  and  washed  metal  from  steel  scrap,  is  of  the 
arc  type.  It  has  an  elliptical  hearth  in  which  are  three  electrodes 
in  line,  which  arrangement  is  claimed  to  give  great  uniformity. 

The  Nathusius  furnace  is  of  the  arc  type  with  additional 
resistance,  and  represents  a  combination  of  the  H6roult  and  the 
Girod  furnace,  the  current  traveling  between  combinations  of 
electrodes  above  and  below  the  bath,  so  that  it  also  passes 
through  the  bath  (Vom  Baur). 


FIG.   20. — Rochling-Rodenhauser  furnace. 
(Eng.  and  Min.  Jour.) 

The  Noble  furnace  is  very  similar  to  the  Gronwall,  Lindblad 
and  Staalhane  shaft  furnace,  differing  from  it  principally  in 
regard  to  the  arrangement  between  the  electrodes  and  the  charge, 
no  space  being  left  between  them.  It  is  sometimes  referred  to 
as  the  Californian  type  of  furnace  from  the  installation  at  He"r- 
oult,  California. 

The  Rennerfelt  furnace  is  of  the  arc  type  and  employs  essen- 
tially a  two-phase  current.  There  are  three  electrodes;  the  mid- 
dle one  is  connected  to  the  neutral  point  and  each  of  the  two 
outside  ones  to  a  phase  of  the  two-phase  system.  By  this 
arrangement  of  current  distribution  the  arc  flame  is  forced  down 
on  the  bath,  producing  a  powerful  effect. 

The  RSchung-Rodenhauser  furnace,  sometimes  called  Schb*- 
nawa-Rodenhauser  furnace,  is  a  modification  of  the  Kjellin  fur- 
nace devised  by  Schonawa  and  Rodenhauser  to  obtain  higher 
temperatures,  and  so  be  better  able  to  effect  purification  than 
with  the  original.  It  is  of  the  induction  type  but  in  addition  to 


ELECTRIC  PROCESSES  163 

this  method  of  heating  employs  resistance,  for  which  purpose 
currents  are  introduced  into  the  bath  through  metal  electrodes, 
so  that  a  double  effect  is  obtained.  It  has  a  hearth  of  a  very 
different  shape  from  other  induction  furnaces.  The  furnace  is 
constructed  for  single-phase  or  for  three-phase  alternating  cur- 
rent; in  the  former  case  the  hearth  (composed  of  grooves)  is  like 
two  Kjellin  rings  intersecting  (forming  a  figure  8),  in  the  latter 
case,  like  three.  In  both  cases  these  two  or  three  grooves  or  heat- 
ing channels  open  into  a  distinct  open  hearth,  the  working  cham- 
ber, where  all  the  metallurgical  operations  take  place,  while  the 
grooves,  which  have  a  comparatively  small  cross-section,  form 
the  secondary  circuits  in  which  the  currents  which  heat  the  metal 
are  induced. 

The  Ruthenburg  process  is  a  link  between  magnetic  separation 
and  the  fusion  process.  It  is  used  for  the  purpose  of  agglomerat- 
ing fine  particles  of  magnetically  concentrated  ores,  as  briquet- 
ting  presents  certain  difficulties  or  objections.  The  fine  concen- 
trates are  passed  through  this  furnace,  the  fusion  zone  of  which 
is  a  strong  magnetic  field,  and  the  ore  particles  are  agglomerated. 
If,  in  addition,  carbon  is  added  to  the  ore  before  entering  the 
apparatus,  a  partial  reduction  takes  place  which  is  subsequently 
further  completed. 

The  Schneider  or  Schneider-Creusot  furnace  of  the  induction 
type  and  somewhat  similar  to  the  Kjellin  furnace,  is  employed, 
but  it  is  designed  to  give  better  circulation  of  the  metal.  It  is  on 
the  principle  of  a  water-tube  boiler:  a  large  reservoir  is  connected 
to  the  ends  of  a  tube  at  an  angle,  and  passing  between  the  arms 
of  a  transformer  carrying  the  primary  winding;  one  of  the  legs 
of  the  tube  is  horizontal,  the  other  slightly  inclined.  The 
advantages  claimed  for  such  an  arrangement  are:  energetic 
mixing  of  the  bath;  keeping  the  metal  in  a  closed  chamber; 
the  possibility  of  purification  as  in  an  open  hearth  furnace; 
and  the  production  of  relatively  large  amounts  of  metal. 

Wm.  Siemens'  furnace,  which  was  used  only  for  experimental 
purposes,  was  on  the  arc  principle  and  consisted  of  a  graphite 
crucible  provided  with  two  electrodes:  in  one  form  one  electrode 
entered  through  the  bottom  and  the  other  through  a  hole  in  the 
cover;  in  a  modification  the  electrodes  were  introduced  at  the 
sides;  a  water-cooled  metallic  electrode  was  subsequently  used 
instead  of  the  carbon  one. 

The  Snyder  furnace  is  of  the  arc  type,  being  an  adaptation 
of  Siemens'  original  furnace  with  single  phase  bottom  electrode 
(Vom  Baur). 

Stassano  furnace :  This  is  an  arc  furnace,  nearly  cylindrical 
in  cross-section,  and  rotating  about  a  vertical  axis  inclined  about 
7°  to  the  vertical  (the  furnace  may  also  be  stationary).  It  is 
provided  with  three  or  more  large  cylindrical  electrodes  inserted 
through  the  sides,  and  nearly  meeting  at  the  center,  supplied 
with  a  three-phase  alternating  current.  The  furnace  is  usually 
lined  with  magnesite,  and  the  charge  is  introduced  at  the  top, 
and  the  molten  products  are  tapped  out  at  the  bottom.  This 
furnace  has  generally  been  used  to  produce  steel  direct  from  ore, 


164 


ELECTRIC  PROCESSES 


but  pig  and  scrap  may  also  be  employed  as  in  other  steel-making 
processes.  In  the  former  method,  pure,  finely  ground  ore,  with 
just  the  right  proportion  of  carbon  and  flux,  is  molded  into  bri- 


Electrode 


PIG.  21. — Stassano  furnace:  vertical  section. 


Charging  Door 


—  Electrode 


Spout 


Electrode 


Electrode 


PIG.  22. — Stassano  furnace:  transverse  section. — AA,  of  Fig.  21. 
(Eng.  and  Min.  Jour.) 

quettes  and  subjected  to  heat  from  the  arc.     The  rotation  of  the 
furnace  helps  to  keep  the  ore  and  carbonaceous  matter  in  contact. 
The  Taussig  furnace  is  of  the  direct  resistance  type,  the  charge 
being  contained  in  a  long  narrow  channel. 


ELECTRIC  PYROMETER— ELECTROLYTIC  IRON  165 

The  Vom  Baur  furnace  is  of  the  arc  type,  and  involves  the 
combination  of  a  two-phase,  three-wire  circuit,  three  upright 
electrodes  connected  to  this  circuit,  a  solid  bottom  for  the  furnace 
and  an  oval-shaped  side  wall  of  refractory  material. 

The  Wile  furnace,  of  the  arc  type,  employs  a  three-phase 
current  and  two  top  and  one  bottom  electrode;  it  has  been  used 
for  melting  ferro-manganese,  etc. 

The  number  of  furnaces  bearing  some  distinctive  or  modify- 
ing name  is  steadily  increasing.  While  some  of  them  may  possess 
essential  differences,  the  great  majority  vary  only  slightly  from 
those  now  in  use  or  which  are  known 

Electric  Pyrometer ;  Resistance  Pyrometer. — See  page  208. 

Electric  Resistance  Furnace. — See  page  153. 

Electric  Shears. — See  page  412. 

Electric  Steel. — See  page  153. 

Electric  Surface  Resistance  Furnace. — See  page  153. 

Electric  Tempering. — See  page  230. 

Electric  Welding. — See  page  503. 

Electrically  Driven  Rolling  Mill. — See  page  407. 

Electro-affinity.— See  page  108. 

Electro-cementizing. — See  page  70. 

Electro  -chemical  Cleaning. — Removing  the  scale,  etc.,  from  iron 
objects  by  attaching  them  to  the  negative  pole  in  an  electrolytic 
bath. 

Electro-chemical  Equivalent. — See  page  89. 

Electrode  Volume. — See  page  364. 

Electro -galvanizing. — See  page  371. 

Electro-iron. — Iron  produced  electrolytically. 

Electrolysis. — (i)  General:  see  page  89;  (2)  for  iron:  see  Electro- 
lytic Iron;  (3)  in  corrosion:  see  page  365. 

Electrolyte. — See  page  89. 

Electrolytic  Corrosion. — See  page  108. 

Electrolytic  Dissociation. — See  page  89. 

Electrolytic  Iron. — That  produced  by  an  electrolytic  process,  the 
anode  consisting  of  metallic  iron  (electrolytic  refining).  It  was 
first  carried  out  successfully  by  Prof.  C.  F.  Burgess  in  1904  by  a 
double  operation.  Typical  analyses  are  given  as  follows  (Trans. 
Am.  Electrochem.  Soc.,  XXV,  489). 


Single  refined 

Double  refined 

O    OOI 

£Jone 

Silicon,  %     

0.003 

0.0013 

Phosphorus    % 

0    020 

o  .  004 

Manganese,  %  
Carbon,  %       

None  - 
o  013 

None 

O.OI2 

99  963 

99  971 

Hydrogen,  %  

o  .083 

0.072 

O.  W.  Storey  (ibid.,  XXIX,  357)  states  that  "at  least  one  of  the 
large  electrical  concerns  is  turning  out  (1916)  1000  pounds  of 
electrolytically  refined  iron  per  week,  with  a  probable  increase  to 


1 66  ELECTROLYTIC  IRON 

several  times  this  output  in  the  near  future.  The  method  used 
is  that  developed  by  Burgess  and  later  modified  by  Watts. 
The  electrolyte  consist r,  of  1 50  grams  of  FeSO4'7H2O,  75  grams 
FeCl2-4H2O,  and  120  grams  (NHOaSC^  per  liter  with  a  specific 
gravity  of  1.125  a*  *<?  C.  Ammonium  oxalate  is  used  as  an 
addition  agent.  The  anodes  consist  of  bars  of  basic  open  hearth 
steel.  The  deposit  reaches  a  thickness  of  %  to  %  inch  be- 
fore it  is  necessary  to  remove  the  cathode  .  .  .  Until 
recently  the  only  use  to  which  electrolytic  iron  had  been  put 
was  in  the  so-called  steel  facing  of  dies  and  electrotypes.'  Its 
hardness,  which  makes  it  suitable  for  such  purposes,  is  due  to 
hydrogen,  either  occluded  or  combined."  In  the  Cowper-Coles 
process  "the  electrolyte  is  a  concentrated  solution  of  ferrous 
chloride  with  additional  organic  compounds,  such  as  the  cresol- 
sulphonic  acids,  and  enough  iron  oxide  to  make  a  sort  of  gruel. 
The  additional  iron  oxide  is  used  for  reducing  the  acidity  and 
polishing  the  iron  which  is  deposited  as  a  sheet  on  a  rapidly 
revolving  cathode  at  a  temperature  near  the  boiling  point  of 
water!  The  current  density  used  is  about  63  amperes  per  square 
foot.  The  resulting  product  is  brittle  due  to  the  presence  of 
several  tenths  of  i  %  of  hydrogen.  It  also  contains  about 
0.50%  of  impurities,  exclusive  of  hydrogen,  while  the  pig 
iron  used  for  anodes  contains  about  7  %.  The  chlorine 
content  ...  is  high"  (ibid.,  358-9).  "In  1913  Cowper- 
Coles  obtained  a  British  patent  in  which  he  proposes  to  avoid 
exfoliation  and  brittleness  ...  by  suspending  an  iron  sponge 
in  an  electrolyte  used  for  refining  iron"  (ibid.,  361).  "In  1911 
Fisher  took  out  patents  ...  in  which  he  claims  that  ductile 
iron  may  be  deposited  from  a  hot  solution  of  ferrous  chloride  if 
hygroscopic  salts,  such  as  the  chlorides  of  calcium,  magnesium,  or 
aluminum  are  added  to  the  electrolyte.  He  claims  that  the 
ductility  of  the  product  increases  with  the  electrolyzing  tempera- 
tures and  that  perfectly  ductile  iron  is  obtained  at  temperatures 
varying  between  100  and  120°  C.  The  preferred  solution  consists 
of  a  highly  concentrated  mixture  of  ferrous  and  calcium  chlorides, 
450  parts  of  ferrous  chloride  and  500  parts  of  calcium  chloride 
being  dissolved  in  700  parts  of  water.  Under  these  conditions  a 
current  density  of  180  amperes  per  square  foot  may  be  used" 
(ibid.,  359).  Ramage  took  out  two  patents,  one  in  191 1  for  the  use 
of  ferric  iron  ore,  dissolved  in  sulphuric  acid  and  reduced  to  the 
ferrous  state  by  sulphur  dioxide,  and  a  later  one  in  which  he 
"dissolves  iron  in  a  ferric  liquor  and  electrolyzes  the  resulting 
ferrous  liquor"  (ibid.,  359-60).  In  Boucher's  process  "the 
electrolyte  is  a  solution  of  one  or  more  ferrous  salts,  such  as  the 
sulphate  or  chloride"  (ibid.,  360).  In  Reed's  process  which  also 
covers  "the  making  of  sulphuric  acid  as  a  by-product.  The 
electrolyte  is  a  solution  of  iron  sulphate.  The  anode  is  made 
of  spongy  lead  which  becomes  sulphated  as  the  electrolysis 
proceeds"  (ibid.,  361).  The  Le  Fer  prp'cess  employs  pig  iron 
as  the  raw  material.  "A  cathode  revolving  in  a  neutral  solution 
of  iron  salts  is  used,  the  solution  being  maintained  neutral  by  the 
circulation  of  the  electrolyte  over  the  surface  of  the  iron"  (ibid., 


ELECTROLYTIC  METHODS— ENGINEERING       167 

361).  In  regard  to  its  properties  Storey  says  (in  part — ibid.,  362) : 
'  Electrolytic  iron  when  deposited  by  the  usual  methods  is  brittle, 
due  to  the  hydrogen  present.  In  this  form  it  can  be  easily 
broken  into  smaller  pieces  and  even  ground  into  powder.  By 
heating  the  iron  to  a  red  heat  the  hydrogen  is  driven  off  and  the 
iron  becomes  ductile,  the  ductility  increasing  with  the  temperature 
of  annealing.  Brittle  electrolytic  iron  as  deposited  is  highly  solu- 
ble in  acids,  being  much  more  readily  soluble  than  zinc.  Annealing 
the  iron  makes  it  become  more  resistant  to  acid  attack  than 
ordinary  irons  and  steels." 

Electrolytic  Methods  of  Etching.— See  page  288. 

Electrolytic  Process. — (i)  For  producing  iron:  see  Electrolytic  Iron; 
(2)  for  coating:  see  Protection,  page  371. 

Electrolytic  Refining. — See  page  165. 

Electrolytic  Theory. — Of  corrosion:  see  page  108. 

Electro-metallurgical  Process. — See  page  153. 

Electron ;  Electron  Theory ;  Electronic  Theory.— See  page  81. 

Electronegative  Ion. — See  page  89. 

Electro-percussive  Welding. — See  page  503. 

Electropositive  Ion. — See  page  89. 

Electro-thermal  (-ic)  Process. — See  page  153. 

Element. — See  page  83. 

Eliquation. — Separating  an  alloy  by  heating  it  so  as  to  melt  the 
more  fusible  of  its  ingredients  but  not  the  less  fusible  (Raymond) ; 
usually  called  liquation:  see  Segregation. 

Ellershausen  Process. — See  page  385. 

Ellis  Process. — See  page  9. 

Elongation. — (i)  General:  see  page  336;  formulae  for:  see  page  338. 

Eisner  Process. — See  page  30. 

Embrittling  (Howe). — Causing  brittleness. 

Embryonic  Crystals. — See  page  1 20. 

Emery. — Impure  corundum  (alumina)  used  for  grinding  and  abra- 
sive purposes. 

Emulsified  Carbide. — Troostite:  see  page  276. 

Eminent  Cleavage. — See  page  124. 

Emissive  Power. — See  page  207. 

Emissivity. — See  page  200. 

Empirical  Formula. — See  page  86. 

Emulsified  Pearlite. — See  page  276. 

Emulsion  Martensite. — See  page  276. 

Enamel ;  Enameling. — See  page  370. 

Encrenee  (Fr.).— See  page  135. 

End  Shears. — See  page  413. 

Endosmose. — See  Solution. 

Endothermic  Reaction. — See  page  82. 

Endurance  Limit. — See  page  333. 

Endurance  Tests. — See  pages  481  and  482. 

Engineering  Standards  Committee,  The  (Brit.).— Organized  for  the 
purpose  of  drawing  up  "British  Standard  Specifications,"  defini- 
tions, and  methods  of  testing  for  various  classes  of  material  and 
objects.     Supported  by  the  following  British  societies: 
The  Institution  of  Civil  Engineers. 


1 68        ENGLISH  BRICK— EUTECTIC  CEMENTITE 

The  Institution  of  Mechanical  Engineers. 
The  Institution  of  Naval  Architects. 
The  Iron  and  Steel  Institute. 
The  Institution  of  Electrical  Engineers. 
English  Brick ;  Dinas  Brick.— See  page  395. 
English  Formula.— For  quality:  see  page  340. 
English  Foundry  Iron  ;  Pig  Irons.— See  page  349. 
English  Scale.— Of  temperatures:  see  page  204 
English  Standard  Wire  Gage. — See  page  187. 
English  Yield  Point.— See  page  471. 
Engorgement.— See  page  35. 
Entering  Angle.— In  rolling:  see  page  407. 
Envelope. — See  page  126. 

Eolotropic  ;  Eolotropy. — A  name  given  by  T.  Gray  to  the  phenome- 
non when  a  flat  bar  shows  greater  elasticity  when  bent  in  one 
direction  than  in  the  other.     This  effect  was  produced  by  heating 
it  in  a  smithy  fire,  whereby  one  side  was  probably  converted  into 
cast  iron  which  had  higher  elasticity  in  compression  than  in 
tension:  see  page  330. 
Equalization  of  Carbon.— See  page  213. 
Equalizer. — (i)  Of  blast:  see  page  34;  (2)  in  cementing:  see  page 

68. 

Equalizing. — In  heat  treatment:  see  page  232. 
Equiaxed  Crystal ;  Grain. — See  page  217. 
Equilibrium. — (i)  General:  see  page  326;  (2)  equation  of:  see  page 

327. 

Equilibrium  Diagram.— See  pages  271  and  327. 
Equilibrium  Temperature. — See  page  327. 
Equivalent. — See  page  87. 
Equivalent  Proportions,  Law  of.— See  page  85. 
Erhardt  Process. — See  page  491. 
Erosion. — See  page  106. 
Etch-polishing. — See  page  288. 
Etching. — See  page  286. 

Etching  Band  ;  Figure ;  Line ;  Pit.— See  page  127. 
Etching  Reagents.— See  page  287. 

Eudiometer. — An  instrument  for  measuring  the  proportions  of 
various  gases  which  are  necessary  to  form  a  given  compound.  It 
consists  of  a  graduated  tube  of  heavy  glass,  sealed  at  one  end,  into 
which  the  gases  are  introduced  and  are  caused  to  explode  by  an 
electric  spark,  the  open  end  of  the  tube  being  held  down  on  a  pad 
during  the  explosion.  The  residual  gases  are  then  measured. 
Euhedral  Crystal. — See  page  122. 

European  Process.— For  malleable  castings:  see  page  258. 
Eurythronium. — See  Vanadium. 
Eustis  Process. — See  page  141. 
Eutectic. — See  page  266. 
Eutectic  Alloy. — See  page  270. 
Eutectic  Austenite. — See  page  275. 
Eutectic  Austenoid. — See  page  275. 
Eutectic  Cast  Iron. — See  page  271. 
Eutectic  Cementite.— See  page  273. 


EUTECTIC  LINE— EXTRUSION  1 69 

Eutectic  Line. — See  page  266. 

Eutectic  Mixture ;  Point ;  Ratio  ;  Solution. — See  page  266. 

Eutectic  Steel. — See  page  273. 

Eutectic  Temperature. — Eutectic  point:  see  page  266. 

Eutectic  Time.— See  page  266. 

Eutecticum. — See  page  266. 

Eutectiferous  Band. — See  page  127. 

Eutectiform  Pattern. — See  page  127. 

Eutectoid. — See  page  270. 

Eutectoid  Cementite. — See  page  273. 

Eutectoid  Ferrite. — See  page  272. 

Eutectoid  Steel. — See  page  273. 

Eutectoid  Transformation. — Of  hypoeutectoid  Steel:  see  page  275. 

Eutectomeric  Alloy. — See  page  4. 

Eutexia. — See  page  267. 

Eutropic  Mixture  ;  Point. — See  page  270. 

Evans  and  Spencer  Process. — See  page  64. 

Evaporation. — See  page  202. 

Evaporative  Power. — See  page  203. 

Even  Fracture.— See  page  178. 

Ewing  and  Rosenhain's  Theory. — Of  slip  bands:  see  page  282. 

Excess  Cementite. — See  page  273. 

Excess  Ferrite. — See  page  272. 

Excess  Substance. — See  page  266. 

Exchanges,  Law  of. — See  page  200. 

Exfoliation. — See  page  68. 

Exhaust  Tuyere. — See  page  32. 

Exhaustion. — Of  cement:  see  page  67. 

Exhaustion  Method. — For  the  removal  of  gases  from  liquid  steel  by 

creating  a  vacuum;  tried  but  not  practical. 
Exosmose. — See  Solution. 
Exothermic  Reaction. — See  page  82. 
Expanded  Metal. — Sheets  in  which  a  series  of  short,  disconnected, 

transverse  cuts  have  been  made,  and  the  sheets  then  extended 

longitudinally,  producing  the  effect  of  a  framework  or  grille. 
Expanding  Cupola. — See  page  182. 
Expansion. — (i)  General:  see  page  204;  (2)  coefficient  or  factor  of: 

see  page  204. 

Expansion  Crack. — See  Crack. 
Expansion  Pyrometer. — See  page  205. 
Explosion  Door. — See  page  33. 
Extension. — See  page  336. 
Extensometer. — See  page  471. 
Exterior  Shrinkage. — See  page  54. 
External  Conductivity.— See  page  200. 
External  Forces. — See  page  331. 
Extra  Lattens. — Of  sheets:  see  page  433. 
Extraction  Process. — One  where  a  metal  is  smelted  or  reduced  from 

its  ore. 

Extrapolation. — See  Curve. 

Extrusion. — The  forcing  of  a  substance  through  a  die  or  aperture. 
Extrusion,  Centrifugal. — See  page  121. 


1 70  EXUDE— EYERMANN  PROCESS 

Exude. — To  ooze  out,  either  under  heat  or  pressure,  e.g.,  for  a  more 
fusible  or  a  softer  substance  to  exude  from  one  which  is  less  fusible 
or  harder. 

Eye. — (i)  The  peep  hole,  covered  with  glass,  in  the  tuyere  of  a 
blast  furnace;  (2)  the  hole  for  the  pin  in  the  end  of  an  eye  bar. 

Eye  Piece.— See  page  285. 

Eyermann  Process. — See  page  318. 


F. — (i)  Fahrenheit  scale:  see  page  204;  (2)  chemical  symbol  for 
fluorine:  see  page  84. 

Fe. — Chemical  symbol  for  iron  (Latin,  ferrum),  q.v. 

Fl  (rare). — Chemical  symbol  for  fluorine:  see  page  84. 

F.  P. — Freezing  point. 

Face. — Of  a  crystal:  see  page  119. 

Face-hardened  Armor  Plate. — See  page  8. 

Faceless  Crystal. — See  page  122. 

Facing  Sand. — See  page  298. 

Faggot  (Eng.);  Fagot ;  Fagoted  Iron. — See  page  378. 

Fahrenheit  Scale. — Of  temperatures :  seepage  204. 

Falk  Method. — See  page  65. 

Fall. — (i)  Of  meteorites:  see  page  290;  (2)  of  malleable  castings: 
see  page  257. 

Fall  of  the  Beam. — See  page  469. 

Falling  Seam. — See  page  489. 

Falling  Weight  Test.— Drop  test:  see  page  481. 

False  Block. — See  page  195. 

False  Pass. — See  page  405. 

Fament  Process. — See  page  385. 

Faraday's  Laws. — See  page  89. 

Faraday's  Theory. — Of  passivity:  see  page  364. 

Farrar  Process. — See  page  385. 

FatT Coal.— See  Coal. 

Fat  Lime.— See  Flux. 

Fat  Sand. — Sand  for  molding  which  contains  a  large  amount  of  clay 
or  alumina.  • 

Fatigue.— See  page  333. 

Fatigue  Limit ;  Stress.— See  page  333. 

Fatigue  Test.— See  page  482. 

Fauld  (obs.). — The  tymp  arch  or  working  arch  of  a  jfurnace  (Ray- 
mond). 

Faulting  Foliation. — See  page  124. 

Feather. — See  page  58. 

Feed  Roll.— See  page  415. 

Feeder ;  Feeding  Gate ;  Feeding  Head. — See  pages  56  and  299.' 

Felsitic  Structure.— See  page  125. 

Fermentation  (obs.). — The  boiling  stage  in  the  puddling  process. 

Fern  Leaf  Crystal. — See  page  122. 

Ferranti  Process. — See  page  155. 

Ferrate. — A  chemical  compound:  see  Iron. 

Ferrated  Carbides.— See  page  278. 

Ferric  Acid. — See  Iron. 

Ferric  Oxide  Theory. — Of  puddling:  see  page  378. 

Ferrite. — (i)  A  chemical  compound:  see  Iron;  (2)  pure  iron:  see 
page  272. 

Ferrite  Ghost.— See  page  289. 

171 


1 7  2  FERRITE  POINT— FILLET 

Ferrite  Point. — See  page  273. 

Ferrite-refinement  Principle. — See  page  341. 

Ferrite  Steels. — Those  consisting  principally  of  ferrite;  hypo-eu- 

tectic  steels. 

Ferro-Alloys. — See  page  351. 
Ferro-Aluminum. — See  page  351. 
Ferro-Brass. — See  page  372. 
Ferro-Carbon. — See  page  351. 
Ferro-Carbonyl. — See  Carbon. 
Ferro-Chrome ;  Ferro -Chromium. — See  page  352. 
Ferro -Ferrite. — See  page  272. 
Ferro-Manganese. — See  page  352. 
Ferro-Molybdenum. — See  page  353. 
Ferro-Molybdenum  Hardenite. — See  page  275. 
Ferro-Nickel. — See  page  353. 
Ferronite. — See  page  277. 
Ferro-Phosphorus. — See  page  353. 
Ferro-Products. — See  page  351. 
Ferro -Silicon. — See  page  354. 
Ferro-Sodium. — See  page  355. 
Ferrostatic  Pressure. — See  page  56. 
Ferro-Steel. — A  trade  name  for  semi-steel  (q.v.). 
Ferro-Titanium. — See  page  355. 
Ferro -Tungsten. — See  page  355. 
Ferro -Vanadium. — See  page  356. 
Ferrous  Acid. — See  Iron. 
Ferrous  Alloy. — See  Alloy. 

Ferrous  Structure. — That  of  ordinary  or  carbon  steels  or  cast  irons. 
Ferruginous. — Carrying  or  containing  iron. 
Ferruginous  Manganese  Ore. — See  page  245. 
Ferro-Concrete. — Reinforced  concrete. 
Fery  Pyrometers. — See  page  207. 
Ftetch  Up. — Of  carbon:  see  Recarburization. 
Fettling. — (i)  Of  castings:  see  page  58;  (2)  of  a  furnace:  see  pages 

315  and  376. 

Fiat  Gage.— See  page  187. 
Fiber;  Fibre. — See  pages  125  and  337. 
Fiber  Stress. — See  page  337. 
Fibriform  Structure. — See  page  125. 
Fibrous  Fracture. — See  page  178. 
Fibrous  Iron  (obs.). — Wrought  iron  which  is  tough,  comparatively 

soft,  and  neither  cold  nor  red-short  in  a  sensible  degree  (Percy). 
Fibrous  Silica. — See  Salamander. 
Fibrous  Structure. — See  page  125. 
Fibrox. — See  page  398. 
Field. — Seepage  291. 
Field  Coat. — See  page  365. 
Fiery  Fracture. — See  page  178. 
Figure  of  Merit. — See  pages  8  and  340. 
Filament. — See  page  125. 
Fill  Out. — In  rolling:  see  page  414. 
Fillet.— The  curved  junction  of  two  surfaces  which  would  otherwise 


FIN— FIRST  STRAND  173 

meet  at  an  angle.     Its  object  is  to  lessen  the  danger  of  cracking, 

and  it  is  used  particularly  in  connection  with  castings,  machined 

material,  and  rolled  sections. 
Fin. — See  Forging. 

Final  Additions. — See  Recarburization. 
Final  Slag.— See  Slag. 
Find. — See  page  290. 
Fine-grained  Fracture. — See  page  1 78. 

Fine-grained  Iron ;  Metal ;  Pig. — Pig  iron  having  a  fine  fracture. 
Fine  Metal. — See  page  383. 
Finer. — See  page  316. 
Finer's  Bar. — See  page  75. 
Finer's  Metal. — See  page  383. 
Finery ;  Finery  Fire. — See  page  382. 
Finger. — See  page  411. 
Fining.— See  page  383. 
Finished. — Material  which  is  ready  for  the  market  without  any 

further  treatment.     Blooms  and  similar  material  are  termed 

semi-finished,  except  only  when  they  are  sold  as  such,  when  they 

may  be  called  finished. 
Finished  Black  Plate. — See  page  431. 
Finished  Charcoal  Bar. — See  page  75. 
Finished  Iron. — A  name  sometimes  applied  to  merchant  (wrought 

iron) ;  muck  bar  piled  and  rerolled. 
Finished  Material  Analysis. — See  page  82. 
Finished  Products. — (i)  General:  see  page  411;  (2)  mills  for:  see 

page  413. 

Finisher. — See  page  316. 
Finishing  Block. — See  page  508. 
Finishing  Metal. — See  Recarburization. 
Finishing  Rolls  ;  Stand. — See  page  414. 
Finishing  Temperature. — See  page  218. 
Finkelstein's  Theory. — Of  passivity:  see  page  364. 
Fir-tree  Crystal. — See  page  122. 
Fire  Assaying. — See  page  82. 
Fire  Bar ;  Bed.— See  page  183. 
Firebrick. — See  page  396. 
Fire  Bridge. — See  page  183. 
Fireclay ;  Fireclay  Brick. — See  page  396. 
Fireclays,  Grades. — See  page  396. 
Fire  Crack. — (i)  In  rolling:  see  page  405;  (2)  of  refractories:  see 

page  395. 

Fire  Gases. — See  page  202. 
Fire  Hole. — See  page  114. 
Fireplace. — See  page  183. 
Firestone. — See  page  395. 
Firing  Test.— See  page  482. 
First  Annealing. — Of  sheets:  see  page  431. 
First  Class  Foam  Cells. — See  page  121. 
First  Order  Cells. — See  page  121. 
First  Pickling. — Of  sheets:  see  page  431. 
First  Strand.— See  page  415. 


174         FISHER  PROCESS— FLUID  COMPRESSION 

Fisher  Process. — See  page  166. 

Fissile. — See  page  124. 

Fissure. — See  Crack. 

Fix  (Eng.). — See  page  376. 

Fixed  Carbon. — See  Fuel. 

Fixed  Converter. — See  page  17. 

Fixed  Elements. — See  page  70. 

Fixed  Furnace. — See  page  312. 

Fixed  Points. — Of  a  temperature  scale:  see  page  204. 

Flake. — See  pages  71  and  178. 

Flame. — See  page  203. 

Flame  Contact  Furnace. — See  page  181. 

Flame  Cut. — Of  material  cut  by  means  of  an  oxyacetylene  or 
oxyhydrogen  flame. 

Flame  Furnace. — See  page  181. 

Flameless  Combustion. — See  page  203. 

Flanch  (obs.). — Flange. 

Flange  Steel. — Steel  of  suitable  quality  to  be  bent  (flanged)  cold. 

Flanging. — See  Cold  Working. 

Flash. — See  Forging. 

Flash  Annealing.— See  page  232. 

Flash  Heating. — See  page  228. 

Flash  Point. — See  page  202. 

Flask. — See  page  297. 

Flask  Annealing.— See  page  58. 

Flat ;  Flat  Iron ;  Flat  Bar  Iron. — A  long  narrow  strip  or  plate,  usually 
produced  on  a  bar  or  merchant  mill. 

Flat  Roll. — See  page  404. 

Flatter. — In  forging,  a  swage  used  to  flatten. 

Flatting  Mill. — A  machine  for  flattening  wire. 

Flavite. — See  pages  69  and  279. 

Flaw.— Defect. 

Flexure ;  Flexural  Rigidity ;  Resilience ;  Strength ;  Stress. — See 
pages  330  and  33  7. 

Flicker  Photometer. — See  page  208. 

Flint  Hardness. — See  Hardness. 

Floating. — Of  cores:  see  page  298. 

Flohr  Process. — See  page  21. 

Floor  Sand. — See  page  301. 

Floss;  Floss  Hole. — See  page  375. 

Flow. — See  page  209. 

Flow  Gate. — See  page  299. 

Flow  Lines. — See  pages  283  and  289. 

Flue. — A  passage  for  air  or  other  gases. 

Flue  Bridge. — See  page  183. 

Flue  Cinder. — See  page  375. 

Flue  Dust. — See  pages  33  and  44. 

Fluid  Bottom. — See  Lining. 

Fluid  Compressed  Steel. — Steel  which  has  been  subjected  to  com- 
pression before  it  has  entirely  solidified:  see  page  63, 

Fluid  Compression.— See  page  63. 


FLUID  METAL— FLUX  1 7  5 

Fluid  Metal. — Suggested  by  Von  Ehrenwerth  for  slagless  iron 
products. 

Fluid  Movement. — See  page  281. 

Fluid  Pig  Iron. — Suggested  by  Von  Ehrenwerth  to  replace  hot 
metal. 

Fluid  Rolling  Process,  Norton.— See  page  65. 

Fluid  Stress. — See  page  332. 

Fluorspar. — Also  called  spar  or  calcium;  fluoride  of  calcium, 
CaF2;  used  as  a  flux:  see  below. 

Flush. — See  pages  36  and  438. 

Flushed  Bars. — See  page  71. 

Flushing  Hole. — See  page  32. 

Flussofen. — See  page  135. 

Flute ;  Fluting. — In  a  plate  which  has  been  rolled  out  longer  on  one 
side  than  on  the  other;  when  it  is  straightened  the  long  side 
shows  flutes. or  waves;  where  the  center  has  been  rolled  out 
longer  than  the  outside,  producing  the  same  effect  in  the  middle, 
the  plate  is  said  to  be  buckled. 

Flux. — (i)  In  the  crucible  process:  see  page  115;  (2)  in  welding: 
see  page  501. 

Flux. — A  material  used  in  smelting  metals  for  the  purpose  of 
combining  with  the  gangue  of  the  ore  and  producing  a  suitable 
slag  (a)  by  making  it  sufficiently  fusible,  and  (6)  by  combining 
with  certain  impurities  and  preventing  them  from  entering 
or  remaining  in  the  metal.  The  term  is  also  used  for  a  sub- 
stance added  in  a  refining  (oxidizing)  process  to  make  the  slag 
more  fusible.  A  flux  may  be  either  acid  or  basic  depending 
upon  its  chemical  properties.  The  principal  basic  flux  is 
limestone,  CaCO3,  also  called  lime,  or  raw  limestone  occurring 
naturally,  and  containing  small  amounts  of  silica,  magnesia, 
alumina,  iron,  etc.  In  color  it  is  ordinarily  gray,  white,  or 
slightly  yellow,  and  is  massive  (non-crystalline)  in  structure. 
If  crystallized,  it  is  known  as  calcite.  For  blast  furnace  work 
the  silica  should  generally  be  less  than  5  %,  and  for  basic  Bessemer 
and  basic  open  hearth  practice  not  over  i  or  2%.  The 
magnesia,  as  well  as  the  iron  and  alumina,  is  not  especially 
objectionable  for  its  use  as  flux,  but  as  a  rule  they  are  less  than 
4%.  The  material  is  sometimes  calcined  to  expel  the  carbonic 
acid,  but  the  action  is  usually  not  perfectly  complete;  it  is  then 
termed  burnt  lime  or  quick  lime.  If,  owing  to  imperfect  calcina- 
tion or  the  presence  of  other  substances  it  slacks  with  difficulty 
(better,  however,  with  hot  water)  it  is  designated  as  poor  lime ; 
if  it  slacks  easily,  as  fat  lime.  Magnesia  and  dolomite  do  not 
find  much  application  as  fluxes  (see  Refractories).  Fluorspar 
or  calcium  fluoride,  CaF2,  sometimes  called  spar,  occurs  in 
translucent  or  transparent  crystals,  which  may  be  colorless, 
light  yellow,  or  purple  in  color.  It  should  contain  less  than  10% 
of  impurities,  but  calcite,  which  is  frequently  present,  is  not  par- 
ticularly objectionable;  the  silica  should  be  less  than  2  %.  A  by- 
product, sometimes  employed,  contains  about  50%  of  calcium 
fluoride  mixed  principally  with  lime;  this,  as  well  as  fluorspar,  is 
occasionally  called  calcium.  This  flux  is  used  principally  in 


1 76  FLUX  LINE— FORGING 

open  hearth  practice  for  thinning  basic  slags  which  are  too 
viscous.  Calcium  chloride,  alkaline  salts,  etc.,  are  sometimes 
used  in  purification  processes  (q.v.).  The  only  acid  flux  is  sand, 
which  is  practically  never  used  as  an  addition  to  a  slag  which  is 
too  viscous  from  high  lime:  it,  as  well  as  borax,  is  used  in  weld- 
ing (q.v.)  to  obtain  a  fusible  cinder. 

McClenahan's  process  for  smelting  certain  southern  red  iron 
ores  was  to  use  common  salt  (NaCl)  instead  of  limestone,  claim- 
ing that  "limestone  has  no  affinity  for  the  aluminous  components 
of  the  red  ore." 

Flux  Line  ;  Stick. — See  page  115. 

Fly.— See  Ladle. 

Fly  Hammer. — See  page  196. 

Flyer.— See  Cold  Working. 

Flying  Shears. — See  page  413. 

Foam;  Foam  Cell ;  Wall. — See  page  121. 

Foaming. — See  Frothing. 

Foeppl's  Method. — Of  determining  hardness:  see  page  478. 

Foerster  and  Schmidt  Theory. — Of  passivity:  see  page  364. 

Folding. — See  page  124. 

Foliation. — See  page  1 24. 

Forbes  Process. — See  page  369. 

Forced  Solution. — See  page  279. 

Fore  Blow. — See  page  21. 

Fore  Hearth. — (ij  Of  a  blast  furnace:  see  page  32;  (2)  of  an  open 
hearth  furnace:  see  page  315. 

Fore  Plate. — See  page  415. 

Fore-Spar  Plate. — See  page  135. 

Foreign  Pig  Iron. — See  page  344. 

Forge. — (i)  To  work  a  piece  of  metal  with  a  hammer  or  a  press; 
(2)  a  power  hammer;  (3)  a  plant  for  the  manufacture  of  (wrought) 
iron  blooms  direct  from  the  ore:  see  page  134;  it  consists  of  a 
furnace  or  forge  fire,  a  blowing  apparatus  and  a  hammer;  (4) 
later,  this  term  was  applied  to  that  part  of  a  (wrought)  iron 
works  where  the  balls  were  hammered  or  squeezed,  and  then 
rolled  into  muck  bar;  that  part  of  the  works  where  the  muck 
bar  was  reheated  and  rerolled  into  finished  iron  was  called 
the  mill. 

Forge  Cinder.— See  Slag. 

Forge  Coal.— See  Coal. 

Forge  Effect. — In  electro-percussive  welding:  see  page  504. 

Forge  Fire. — Forge,  q.v. 

Forge  Iron ;  Pig. — See  page  344. 

Forge  Process.— See  page  74. 

Forge  Rolls  ;  Train.— See  page  413. 

Forging. — The  operation  of  working  metal  or  of  changing  its  shape 
by  striking  it  a  sharp  blow  (usually  while  hot)  with  a  hammer  or 
other  suitable  instrument;  also  the  object  so  produced.  The  ac- 
tion^  of  a  hydraulic  press  is  frequently  termed  forging  (hydraulic 
forging),  but  as  the  action  is  more  of  a  steady  squeeze  the  desig- 
nation pressing  would  appear  to  be  preferable.  To  indicate  the 
use  of  a  hammer,  the  term  hammer  forging  is  employed.  The 


FORGING  CRACK— FRACTURE  1 7  7 

operation  of  hammering  puddle  balls  was  formerly  called  shin- 
gling or  nobbing.  The  term  smithing  (Eng.)  is  sometimes  used 
for  working  a  piece,  especially  by  hammering,  for  the  purpose  of 
straightening  or  flattening  it.  Removing  or  correcting  the  irregu- 
larities of  a  piece  by  hammering  (sometimes  cold)  may  be  referred 
to  as  dressing  or  hammer  dressing.  Where  a  forging,  for 
example  a  projectile,  is  made  by  hot  punching  a  portion  of  its 
length,  the  billet  may  be  placed  in  a  die  and  forced  down  until  it 
completely  fills  it,  an  operation  known  as  setting  down.  Drop 
forging  (and  the  object)  is  a  process  designed  for  making  a  large 
number  of  objects  exactly  the  same.  It  consists  in  forging  a 
suitable  piece  of  steel  between  dies  under  a  hammer,  the  lower 
die  being  attached  to  the  anvil  block,  while  the  upper  is  fastened 
to  the  hammer  itself,  and  moves  up  and  down  with  it.  When  the 
object  is  simple,  one  set  of  dies  may  suffice,  but  with  more  com- 
plicated pieces,  two  or  more  are  necessary  for  roughing  and  finish- 
ing. The  fin  or  flash,  formed  at  the  sides  of  the  piece  where  a 
small  portion  of  the  metal  is  forced  out  between  the  edges  of  the 
dies,  is  dressed  off,  and  any  other  required  machining  is  done. 
Hollow  forging  is  where  a  piece,  usually  a  heavy  shaft  or  column, 
is  bored  and  then  forged  out  on  a  mandrel.  Its  object  is  to  secure 
better  working  of  the  metal  than  would  be  the  case  with  a  solid 
piece  of  large  cross-section.  See  also  Hammer  and  Press. 

Forging  Crack. — See  Crack. 

Forging  Strain. — A  strain  set  up  in  forging  at  too  low  a  temperature, 
or  where  a  part  receives  more  work  than  another. 

Forging  Test.— See  page  476. 

Form. — Mold. 

Formation  of  Crystals. — See  page  120. 

Former. — See  page  405. 

Formula. — Chemical  Formula:  see  page  86. 

Fornoconvertisseur. — See  page  318. 

Forsyth  Process. — See  page  62. 

Forty-eight-hour  Coke. — See  page  95. 

Fosberg's  Swedish  Hearth. — See  page  76. 

Fossil  Ore ;  Fossilif  erous  Red  Hematite. — See  page  244. 

Foster  Pyrometer. — See  page  207. 

Foul  Gas  Main. — See  page  96. 

Founding ;  Foundry.— See  page  53. 

Foundry  Coke. — See  page  96. 

Foundry  Iron ;  Pig. — See  page  344. 

Foundry  Pit. — See  page  57. 

Four-high  Mill,  Bleckley's. — See  page  417. 

Four-sided  Charcoal  Wire. — See  page  509. 

Fournier  Pyrometer. — See  page  209. 

Fox  Tail.— See  page  79. 

Fracture. — The  irregular  surface,  and  its  appearance,  produced 
when  a  piece  of  metal  is  ruptured  or  broken.  The  terms  fracture 
and  rupture  are  frequently  used  interchangeably;  it  is,  however, 
desirable  to  restrict  them  as  just  indicated. 

Howe  (Metallog.,  527-8)  classifies  fractures  as  follows: 
12 


1 78  FRACTURE 

1.  Granular  or  intergranular,  caused  by  rupture  passing  along 
grain  boundaries  instead  of  across  the  crystalline  grains  them- 
selves. 

2.  Crystalline,  trans-crystalline,  or  intra-crystalline,  caused 
by  rupture  passing  across  the  crystalline  grains  themselves. 

3.  Silky,  caused  by  the  thread-like  drawing  out  of  the  frag- 
ments of  the  crystals  in  the  act  of  rupture. 

4.  Hackly  or  hooked,  sharp  or  jagged  and  irregular,  which  may 
be  referred  to  the  drawing  out  of  the  ferrite  in  the  act  of  rupture. 

5.  Fibrous  and  slaty,  caused  by  rupture  occurring  consecutively 
through  distinct  layers. 

6.  Columnar,  as  in  the  case  of  the  outer  parts  of  ingots  and  other 
castings  of  quiet  or  piping  steel. 

Granular  fractures  better  reflect  the  light  than  those  which  are 
trans-crystalline;  they  are  also  more  frequent  with  overheated  or 
highly  heated  steel  and  are  called  coarse-grained,  rough,  bright 
crystalline,  bright,  or  granular-crystalline ;  if  especially  coarse  and 
bright,  brilliant,  splendent,  sappy,  or  fiery  and,  in  the  case  of 
crucible  steel  held  too  long  in  the  pot,  scorched  or,  if  pieces  of 
fuel  have  fallen  in,  staring.  Where  tool  steel  or  other  steel  high 
in  carbon  has  been  heated  in  such  a  way  as  to  convert  some  of  the 
carbon  into  graphite,  it  is  said,  from  the  appearance,  to  have  a 
black  fracture. (or  black  center).  Flaking  is  the  scaly  fracture  in 
high-speed  steels  due  to  being  soaked  at  high  temperatures  and 
afterwards  not  forged  sufficiently  to  break  up  the  coarse  grain; 
this  condition  disappears  on  annealing,  but  reappears  on  rehard- 
ening  (Brearly ) .  The  trans-crystalline  fractures  are  also  referred 
to  as  fine  grained,  smooth,  even,  or  amorphous,  but  preferably  for 
the  last  should  be  used  the  terms  porcelanic  or  aphanitic  ;  due 
to  the  absence  of  pronounced  luster  they  are  also  called  dull  or, 
more  rarely,  gray-granular. 

If  wrought  iron  is  nicked  all  around  and  broken  short  off  with 
a  sharp  blow,  the  fracture  may  be  granular;  but  if  nicked  on  only 
one  side,  and  bent  slowly  away  from  the  nick,  the  intermingled 
slag  causes  the  iron  to  break  in  layers,  and  the  fracture  is  barked, 
fibrous,  laminated,  or  splintery.  Such  an  appearance  is  not  often 
found  in  the  case  of  plain  carbon  steel,  but  is  obtained  with 
screw  stock  grade  (high  in  manganese  sulphide),  also  with  certain 
alloy  steels,  especially  those  containing  nickel.  Material  which 
has  been  broken  at  one  time,  as  by  a  single  blow,  so  quickly  that 
the  piece  snaps  off  without  any  appreciable  bending,  gives  rise 
to  a  brittle  fracture  or  sudden  fracture,  in  contradistinction  to  the 
tough  fracture  resulting  from  considerable  bending  and  tearing. 

If  the  fracture  shows  very  sharp  points  it  is  sometimes  called  a 
needle  fracture ;  if,  as  in  the  case  of  certain  zinc-copper  or  tin- 
copper  alloys,  it  has  the  appearance  of  a  number  of  little  shells,  it 
is  termed  conchoidal. 

A  star  fracture  is  the  term  applied  to  the  fracture  of  certain 
broken  tensile  test  specimens,  which  are  generally  found  only 
when  the  elastic  limit  is  about  90,000  Ibs.  per  square  inch  or  over. 
It  has  the  appearance  of  a  star  with  raised  ribs  (or  rays)  radiat- 
ing outwards  from  a  common  center.  A  fracture  is  referred  to  as 


FRACTURE  TEST— FREE  IRON  179 

composite  when  it  consists  of  more  than  one  form  or  type.  An 
irregular  fracture  is  sometimes  spoken  of  as  uneven.  Fractures 
(usually  of  slags,  etc.,  which  are  non-metallic)  having  a  glassy 
appearance  or  shape,  are  termed  vitreous  or  vitriform. 

Where  a  piece  has  broken  under  alternate  bending  stresses, 
the  material  usually  gives  way  gradually,  i.e.,  one  part  at  a  time, 
and  the  first  part  to  give  way  gives  rise  to  rubbing  and  blacken- 
ing of  the  opposed  surfaces,  while  the  last  part  is  usually  more  or 
less  granular;  this  is  known  as  a  progressive  fracture  or  a  detail 
fracture.  Before  rupture  was  complete  there  would  be  found  a 
partial  fracture.  A  detail  fracture  may  be  started  either  on  the 
outside  or  the  inside,  in  the  latter  case  giving  rise  to  an  internal 
fracture  whose  appearance  may  throw  valuable  light  on  the  con- 
dition of  strains  which  brought  it  about.  Detail  fractures  are 
sometimes  attributed  to  what  is  erroneously  termed  cold  crystal- 
lization, it  being  claimed  that  actual  growth  of  the  grain  occurred 
while  the  given  piece  was  in  service.  This  has  been  thoroughly 
disproved  as  regards  ordinary  temperatures  for  iron  and  steel,  and 
was  probably  due  to  the  fact  that  the  fracture  of  a  tensile  test 
specimen,  or  where  there  has  been  considerable  deformation, 
always  has  a  much  finer  appearance  than  where  the  rupture  was 
abrupt. 

Fremonville  investigated  fractures  occurring  in  metals,  by 
means  of  observations  on  ruptured  glass  and  bitumen.  He  enun- 
ciated the  following  laws  in  regard  to  his  bursting  theory:  i.  The 
origin  of  all  breakages  is  a  burst  taking  place  in  the  interior  of  the 
body,  and  only  develops  itself  by  a  succession  of  bursts,  which 
are  general  in  the  case  of  sudden  fractures  and  localized  in  the  case 
of  progressive  fractures.  2.  The  first  burst — the  origin  of  all 
rupture — takes  place  in  a  region  where  the  principal  stress  is 
positive,  but  not  necessarily  at  a  point  where  that  stress  reaches 
its  maximum  value.  Other  things  being  equal,  the  stress  normal 
to  the  principal  stress  determines  the  danger  of  rupture  (Inst. 
Met.,  1915,  I,  318). 

In  tensile  testing,  if  the  metal  is  relatively  soft  and  ductile,  the 
entire  exterior  portion  may  be  extended  more  than  the  interior 
which,  accordingly,  is  depressed,  and  this  effect  gives  rise  to  a 
cup  fracture  ;  if  only  a  portion  of  the  exterior  has  been  so  extended, 
a  half-cup,  etc.  If  the  piece  breaks  at  an  angle,  it  is  called  an 
angular,  oblique,  or  slip  fracture.  If  the  fracture  is  partly 
angular  and  partly  a  cup,  it  is  known  as  an  irregular  fracture. 

Fracture  Test. — See  page  483. 

Fragility. — Brittleness,  q.v. 

Fragmental  Structure. — See  page  125. 

Fragmentation  Test. — See  page  483. 

Franche-Comte  Process. — See  page  76. 

Franklinite. — See  page  244. 

Fredenhagen  Theory. — Of  passivity:  see  page  364. 

Free  Carbon  Dioxide. — See  page  107, 

Free  Cementite. — See  page  2  73. 

Free  Fenite. — See  page  272. 

Free  Iron  (Sorby). — See  page  272. 


1 80  FREE  PHOSPHIDE— FURNACE 

Free  Phosphide. — See  page  289. 

Freedom,  Degree  of. — See  page  327. 

Freezing ;  Freezing  Point ;  Freezing  Point  Curve.— See  page  201. 

Freezing  Range. — See  page  267. 

Fremont  Machine. — For  impact  testing:  see  page  482. 

Fremont's  Method. — To  determine  hardness:  see  page  478. 

French  Calorie. — See  page  199. 

French  Metal. — See  Antimony. 

Fresh  Iron.— See  page  364. 

Freshen. — Sometimes  used  in  the  sense  of  to  purify,  e.g.,  when  air  is 
blown  through  molten  pig  iron. 

Friable. — Easily  crumbled;  reducible  to  powder. 

Frick  Furnace. — See  page  155. 

Friction  Drive. — See  page  418. 

Frigo-Tension.— See  Cold  Working. 

Frischen  Process. — See  page  383. 

Fritting. — Becoming  pasty  and  melting  down  on  heating;  the 
action  of  some  soft  coals. 

Fritz  Mill. — See  page  408. 

Frondescent  Hematite. — See  page  244. 

Frontal  Hammer ;  Helve. — See  page  197. 

Frothing. — Also  called  foaming ;  the  condition  of  a  slag  in  a  refining 
process  which  is  viscous  and  becomes  puffed  up  by  the  carbonic 
oxide  gas  evolved  from  the  oxidation  of  the  carbon  in  the  metal 
underneath. 

Frothy. — (i)  Of  slags,  the  same  as  frothing;  (2)  of  steel,  unsound 
from  foaming  or  rising  in  the  mold. 

Frozen  Continent. — See  page  54. 

Fryer  Process. — See  page  30. 

Fuel. — From  a  commercial  standpoint  a  substance  which  can  be 
burned  economically  for  the  generation  of  heat  to  be  applied 
to  some  useful  purpose.  Fuels  may  be  either  solid,  liquid,  or 
gaseous.  They  consist  of  combustible  matter  (matter  which  will 
burn)  and  ash  or  matter  which  will  not  burn.  The  combustible 
matter  consists  of  carbon  and  hydrogen,  combined  or  uncom- 
bined.  If  the  fuel  is  solid,  the  combustible  matter  is  divided  into 
volatile  matter  which  is  driven  off  upon  the  application  of  heat, 
and  fixed  carbon  which  is  left  behind.  The  residue,  containing 
both  the  fixed  carbon  and  the  ash,  is  sometimes  referred  to  as  the 
coke. 

Fuel  Gas. — Any  gas  suitable  for  use  as  a  fuel;  sometimes  used  more 
particularly  for  producer  gas  or  water  gas. 

Fuliginous  (rare). — Smoky  or  dirty. 

Full  Radiator. — See  page  207. 
•Full-size  Test.— See  page  468. 

Fuller. — A  tool  with  a  face  of  sharp  curvature,  fitting  in  the  socket 
of  an  anvil,  on  which  bars  are  hammered  down. 

Furgen  (obs.). — A  round  rod  used  for  sounding  a  bloomary  fire 
(Raymond). 

Furnace. — A  structure  in  which  heat  is  generated  by  the  com- 
bustion of  fuel,  more  particularly  for  the  smelting  of  ore  or 
the  treatment  of  metal.  They  may  be  classified  according  to: 


FURNACE  181 

I.  The  nature  of  the  fuel: 

1.  Solid  fuel:  coal,  coke  or  charcoal  furnace. 

2.  Liquid  fuel:  oil  furnace. 

3.  Gaseous  fuel:  gas  furnace. 
II.  Method  of  applying  the  heat: 

4.  Direct  heating  furnaces,  where  the  fuel  or  flame  comes  in 
contact  with  the  charge: 

(a)  Contact  heating  furnaces,  where  solid  fuel  is  in  contact 
or  mixed  with  the  material  to  be  heated,  as  in  the  blast 
furnace. 

(b)  Flame  contact  furnace  or  flame  furnace,  where  only 
the  flame  strikes  the  charge,  as  in  a  reverberatory 
furnace. 

5.  Indirect  heating  furnaces,  where  the  charge  does  not 
come  in  contact  with  either  the  fuel  or  the  flame,  but  is 
heated  by  conduction  and  radiation  through  a  wall,  as  in  a 
muffle  furnace. 

III.  The  form  or  construction  of  the  furnace.     This  classifica- 

tion will  be  more  particularly  followed  below. 

IV.  The   purpose   for  which    the    furnace    is    intended,    e.g., 

an  annealing  furnace.  Except  where  a  special  type 
is  introduced,  such  furnaces  will  be  found  discussed  in 
connection  with  the  special  process  involved. 

Heap,  pile,  or  mound:  This  is  the  oldest  form  of  heating 
arrangement  and  is  employed  only  for  roasting  or  calcining. 
The  material,  mixed  with  solid  fuel,  is  piled  up,  usually  without 
any  covering  (open),  sometimes,  as  in  the  case  of  the  old  method 
for  the  preparation  of  charcoal,  covered  with  earth  or  turf, 
small  openings  being  left  for  draft. 

Stall:  This  is  somewhat  similar  to  the  heap,  but  usually  has 
brick  walls  on  three  sides,  the  top  and  the  front  being  left  open. 
This  insures  a  more  even  heating  than  the  heap.  It  is  used  for 
roasting  and  calcining,  formerly  also  for  coking  coal. 

Oven:  This  name  is  sometimes  used  synonymously  with 
furnace  (the  German  word  for  furnace  is  Of  en),  e.g.,  a  furnace 
of  the  reverberatory  type  for  drying  molds  is  called  a  drying 
oven.  It  is  principally  restricted  to  furnaces  for  making  coke 
(q.v.);  an  oven  for  annealing  was  called  a  calcar. 

Shaft  furnace:  This  consists  of  vertical  brick  walls,  and  is 
usually  circular  in  cross-section,  with  the  height  several  times 
the  inside  diameter.  The  material  is  charged  at  the  top  and 
removed  at  the  bottom.  The  top  may  be  provided  with  a 
bell  and  hopper  (see  page  32)  or  simply  left  open.  The  fuel 
is  usually  solid  and  is  charged  in  lumps  at  the  top  mixed  with 
the  other  materials,  and  the  air  for  combustion  may  be  sup- 
plied by  natural  draft,  or  more  generally  under  pressure  through 
pipes  or  tuyeres  near  the  bottom.  Oil  or  gas  is  sometimes 
employed  for  fuel,  in  which  case  it  is  injected  with  the  air  through 
similar  pipes  at  the  bottom. 

Kilns  are  shaft  furnaces  for  roasting  or  calcining  ore,  limestone, 
etc.,  where  a  very  high  temperature  is  not  required,  and  may  be 
fired  in  any  of  the  ways  described  above,  but  generally  with  coke, 


I 82  FURNACE 

and  the  employment  of  a  gentle  blast.  They  are  relatively  short, 
up  to  about  30  feet,  and  as  a  rule  are  of  uniform  diameter  through- 
out. A  furnace  of  this  type,  somewhat  resembling  a  beehive  coke 
oven,  is  generally  used  for  firing  bricks  (brick  kiln  or  brick 
oven). 

Cupolas  are  similar  to  kilns  and  are  used  for  melting  pig 
iron.  They  are  usually  of  the  same  diameter  throughout, 
but  may  have  the  walls  slightly  divergent  at  about  the  middle, 
rarely  called  an  expanding  cupola.  They  are  practically  always 
fired  with  coke  and  a  gentle  blast,  generally  cold,  but  occasionally 
slightly  preheated,  in  which  case  it  is  termed  a  hot-blast  cupola, 
and,  in  contradistinction,  the  former  would  be  referred  to  as  a 
cold-blast  cupola.  The  blast  may  be  supplied  to  each  tuyere 
separately  from  a  fan,  but  usually  through  a  casing  surrounding 
the  furnace,  similar  to  the  bustle  pipe  of  a  blast  furnace,  called  an 
air  chamber  or  air  belt.  An  arrangement  is  sometimes  made  by 
which  the  tuyeres  can  be  placed  at  different  levels  (adjustable 
tuyere).  The  bottom  of  the  cupola  is  called  the  hearth  or  well. 
There  are  holes  provided  at  the  bottom  for  tapping  the  molten 
cinder  and  the  iron.  The  tapping  hole  is  closed  with  a  plug  of 
clay  (bod,  bot,  or  bott)  thrust  in  on  the  end  of  an  iron  rod  (bot 
stick) ;  the  operation  of  closing  the  hole  is  sometimes  called  stop- 
ping in  or  hotting  up.  If  the  bottom  is  built  on  a  solid  foundation 
of  masonry,  it  is  called  a  stationary  bottom,  but,  according  to 
modern  practice,  it  is  generally  closed  with  a  hinged  plate  of 
cast  iron  which  can  be  opened  to  dump  the  material  remaining 
in  the  cupola  after  a  run,  and  called  a  drop  bottom.  Foundry 
cupolas  may  have  an  arched  hole  (breast  hole)  above  the  bottom 
which  can  be  opened  for  cleaning  out  the  cupola,  and  is  closed 
with  an  iron  door  (breast  plate).  A  reservoir  cupola,  tank 
cupola,  or  compound  cupola  is  one  with  a  greater  diameter  at  the 
bottom,  or  provided  with  a  connecting  chamber,  so  a  greater 
amount  of  iron  may  be  kept  molten.  A  very  small  furnace  for 
melting  purposes,  which  can  be  picked  up  by  a  crane  for  pouring 
the  molten  iron  into  a  ladle,  has  been  styled  a  cupola  crucible. 
Cupolas  used  in  connection  with  the  Bessemer  process  are  charged 
at  the  top;  foundry  cupolas  through  a  hole  on  the  side  near  the 
top  (charging  door).  A  cupola  is  said  to  be  ready  to  run  when 
the  pig  iron  has  melted.  The  man  in  charge  is  called  the  melter. 

Shaft  furnaces  for  smelting  iron  ore  are  termed  blast  furnaces 
(ff.*). 

Hearth:  This  is  a  rectangular  chamber  of  only  moderate 
depth,  in  which  the  charge  is  heated  in  contact  with  solid  fuel, 
the  walls  and  bottom  of  which  are  usually  of  cast  iron,  frequently 
water-cooled.  If  the  top  is  enclosed  with  a  hood,  it  constitutes 
a  closed  hearth,  otherwise,  an  open  hearth.  The  air  for  combus- 
tion is  blown  in  through  one  or  more  tuyeres.  The  action  may  be 
reducing  when  used  for  some  direct  process  (q-v.)t  or  oxidizing 
when  used  for  refining  (see  Purification  Processes  and  Charcoal 
Hearth  Processes). 

Reverberatory  furnace  (air  furnace) :  In  this  furnace  the  charge 
is  heated,  not  by  direct  contact  with  the  fuel,  but  by  the  gaseous 


FURNACE  183 

products  of  combustion  (the  flame)  and,  as  a  rule,  no  blast  is 
employed.  Where  a  very  strong  draft  is  maintained  it  may  be 
termed  a  wind  furnace.  It  consists  of  the  heating  chamber, 
called  the  hearth  or  laboratory,  on  the  bottom  or  sole  (also  called 
the  hearth  or  rarely  the  firebed).  of  which  the  charge  rests.  At 
one  end  is  a  small  chamber  (fireplace)  in  which  the  fuel  is  burned; 
at  the  other  end  the  chimney  or  stack.  At  each  end  of  the  hearth 
is  a  low  wall  (bridge  or  bridge  wall);  that  next  the  fireplace  is 
called  the  fire  bridge  ;  that  next  the  chimney,  the  flue  bridge  or 
altar.  The  roof  usually  has  a  very  flat  arch,  springing  from  the 
side  walls,  and  covers  both  the  fireplace  and  the  hearth;  it  is 
highest  over  the  fireplace,  and  thence  slopes  downward  to  the 
chimney  flue,  so  that  the  flame,  after  striking  the  roof,  will  be 
deflected  down  (reverberated)  upon  the  charge.  If  the  roof  is 
high  enough,  so  that  the  flame  does  not  actually  touch  the  charge, 
which  is  then  heated  by  radiation  from  the  roof,  the  furnace  is 
termed  a  radiation  furnace.  The  fuel  is  usually  solid,  and  is 
supported  on  grate  bars  (fire  bars)  which  may  be  easily  removed  to 
permit  of  cleaning  and  replacement;.  The  furnace  may  be  used 
for  heating  purposes,  or  for  melting  operations  as  in  the  puddling 
process.  In  the  former  case  it  may  be  built  entirely  of  brick 
(with  iron  tie  rods,  etc.),  but  in  the  latter,  the  hearth  generally 
has  cast-iron  sides  and  bottom,  either  air-cooled  or  water-cooled. 
The  charge  is  usually  introduced  through  one  or  more  doors 
(charging  doors)  in  the  side:  for  roasting  purposes,  sometimes 
through  hoppers  in  the  roof. 

Recuperative  furnaces  are  similar  to  ordinary  reverberatory 
furnaces,  but  the  air  for  combustion  (under  a  slight  pressure) 
is  preheated  by  entering  through  pipes  in  the  chimney  flue, 
around  which  the  products  of  combustion  pass. 

Regenerative  furnaces  are  special  reverberatory  furnaces 
using  either  gaseous  or  liquid  (practically  never  powdered) 
fuel,  in  which  the  air  alone,  or  both  the  air  and  the  fuel,  are  pre- 
heated in  special  chambers  (regenerators)  situated  at  each  end 
of  the  furnace,  between  the  furnace  and  the  stack  (see  Heat). 
In  this  arrangement  the  air  and  fuel  are  burned  alternately  at 
each  end,  one  set  of  regenerators  being  heated  by  the  products 
of  combustion  while  on  their  way  to  the  stack,  while  the  other  set 
is  heating  the  air  and  fuel  before  entering  the  furnace  proper. 
In  this  country,  when  this  type  js  used  for  making  steel  it  is 
called  an  open  hearth  furnace  or  a  Siemens  furnace  (see  Open 
Hearth  Process). 

Crucible  furnaces  are  properly  furnaces  in  which  crucibles 
(q.v.)  are  heated  and  may  be  of  various  types.  The  crucibles 
may  be  set  directly  on  the  solid  fuel,  supported  on  grate  bars  in  a 
small,  short,  shaft  furnace;  heated  in  similar  chambers  with  gas 
preheated  in  regenerators  (regenerative  crucible  furnace) ;  or  on 
the  hearth  of  a  regenerative  reverberatory  (open  hearth)  furnace. 

Muffle  furnaces  consist  of  a  closed  chamber  in  which  the 
charge  is  heated  out  of  contact  with  the  fuel  or  the  products 
of  combustion.  Converting  furnaces  (used  for  cementation) 
are  of  this  type,  but  are  frequently  termed  retort  furnaces.  In 


184         FURNACE  ADDITIONS— FURNACE  TEST 

England  this  name  is  sometimes  applied  to  a  fire  used  for  heating 
crucible  steel  ingots,  etc.,  similar  to  a  smith's  forge,  consisting  of 
a  hollow  fire  made  with  large  lumps  of  coal  and  blown  with  a  fan 
blast,  bricks  and  a  few  plates  being  used  to  confine  the  fire  (Har- 
bord  and  Hall). 

Retort  furnaces  are  properly  those  used  (in  non-ferrous  metal- 
lurgy) for  distilling  (volatilizing)  metals,  etc.,  as  in  the  purification 
of  zinc.  They  contain  a  chamber  in  which  the  material  is  heated 
out  of  contact  with  the  fuel  or  gases,  and  a  flue  leading  to  a 
condensing  (cooling)  chamber;  they  may  be  similar  to  a  muffle 
or  a  crucible  furnace. 

Heating  furnaces  or  reheating  furnaces  are  those  used  for 
heating  solid  pieces  of  iron  or  steel  to  a  temperature  suitable  for 
rolling,  forging,  etc.  They  are  usually  of  the  ordinary  or  regener- 
ative reverberatory  type,  and  the  names  given  above  are  used 
more  generally  for  those  which  are  built  above  the  floor  level,  and 
in  which  the  material  is  charged  horizontally  through  doors  in  the 
,side  (horizontal  heating  furnace),  as  in  reheating  billets,  slabs, 
etc.  A  special  type,  buijt  below  the  floor  level,  and  charged 
through  the  top  (vertical  heating  furnace),  is  employed  for  heat- 
ing ingots  which  are  usually  charged  before  they  have  completely 
solidified,  and  hence  must  be  kept  in  a  vertical  position  to  have 
the  pipe  in  the  top.  Such  furnaces  are  called  soaking  pits,  soak- 
ing furnaces,  or  pit  heating  furnaces.  They  are  generally  pro- 
vided with  regenerators,  but  the  original  type  (Gjers  pit ;  soaking 
pit  process)  did  not  employ  any  fuel,  the  heat  of  the  still  molten 
interior  of  the  ingot  being  depended  upon  to  bring  the  exterior 
portion  to  the  proper  temperature;  the  action  whereby  the 
heat  diffuses  is  termed  soaking. 

A  continuous  furnace,  strictly  speaking,  is  one  which  is  charged 
at  one  end  and  drawn  (or  tapped)  at  the  other.  This,  of  course, 
includes  such  types  as  the  blast  furnace,  but  is  generally  con- 
sidered to  mean  a  continuous  heating  furnace  which  is  of  the 
reverberatory  type,  but  longer  than  ordinary,  frequently  recuper- 
ative, and  used  for  heating  billets,  etc. ;  these  are  charged  cold  at 
the  flue  end  and  are  moved  forward  over  water-cooled  pipes  (with 
rounds,  they  may  simply  roll  down  by  gravity)  by  hydraulic 
pushers,  and  are  drawn  at  the  fire-place  end. 

Furnace  Additions. — See  Recarburization. 

Furnace  Amianthus. — See  Salamander. 

Furnace  Annealing. — See  page  232. 

Furnace  Coal. — See  Coal. 

Furnace  Coke. — See  page  96. 

Furnace  Cooling. — See  page  232. 

Furnace  Slag. — See  Slag. 

Furnace  Test. — Sometimes  simply  test.  A  portion  of  metal  taken 
from  an  open  hearth  furnace  and  cooled  and  broken  to  determine 
by  the  fracture  the  approximate  amount  of  carbon,  etc.,  in  the 
bath.  If  this  is  sent  to  the  chemical  laboratory,  it  is  frequently 
called  the  preliminary  test.  In  England  it  is  usually  forged 
down  under  a  hammer  before  quenching  and  breaking  to  deter- 
mine its  freedom  from  red-shortness. 


FUSE— FUSION  POINT  185 

Fuse. — To  melt;  to  liquefy  "by  the  application  of  heat. 

Fused  Silica. — See  page  395. 

Fusible  Alloy. — See  page  4. 

Fusible  Cement. — See  page  69. 

Fusible  Cones. — See  page  209. 

Fusing-point  Pyrometry. — See  page  209. 

Fusion. — (i)  General:  see  page  201;  (2)  zone  in  meteorites:  see 
page  292;  (3)  zone  of  complete  fusion  in  blast  furnace  practice: 
see  page  36;  (4)  zone  of  incipient  fusion  in  blast  furnace  prac- 
tice: see  page  36. 

Fusion  Curve. — See  Curve. 

Fusion  Point. — See  page  201. 


G. — (i)  Gravity,  q.  ».;  (2)  gram  or  gramme. 

Ga. — Chemical  symbol  for  gallium:  see  page  84. 

Gd. — Chemical  symbol  for  gadolinium:  see  page  84. 

Ge. — Chemical  symbol  for  germanium:  see  page  84. 

Gl. — Chemical  symbol  for  glucinum  (at  one  time  called  beryllium) : 
see  page  84. 

G.  M.  V. — Gram-molecular  volume:  see  page  83. 

G.  M.  B. — Good  merchantable  brand  (of  pig  iron). 

G.  M.  W. — Gram-molecular  weight:  see  page  83. 

Gag. — See  Hammer. 

Gag  Press.— See  Straightening  Press. 

Gage. — (i)  The  thickness  of  a  sheet  or  plate;  (2)  an  instrument  for 
measuring  the  dimensions,  etc.,  of  an  object  or  substance;  (3)  a 
table  showing  the  equivalents  of  the  arbitrary  markings  on  a 
fixed  gage.  Among  those  of  more  particular  interest  in  this  con- 
nection are  the  following:  Limit,  plus  and  minus,  or  high  and  low 
gages  are  those  provided  with  two  measuring  devices  correspond- 
ing respectively  to  the  maximum  and  minimum  dimensions  to 
which  the  object  must  conform;  for  example,  in  measuring  a  hole, 
the  minimum  gage  must  enter,  while  the  maximum  gage  must  not. 
Inside  and  outside  gages  are -to  measure  respectively  the  internal 
and  external  dimensions  of  a  hollow  object.  A  stud  gage  is  used 
to  determine  the  proper  spacing  of  two  or  more  holes  as  in  splice 
bars.  For  shrinkage  gage,  see  Molding,  page  296. 

In  the  following  table  are  given  the  various  gages  used  for  wire 
and  sheets  or  thin  plates  (heavier  plates  are  recorded  in  fractions 
of  an  inch  or  other  unit). 

"The  wire  gage  for  which  sizes  are  shown  under  the  title  of 
American  Steel  &  Wire  Co.'s  gage,  was  the  same  as  the  Washburn 
&  Moen  gage,  and  also  the  same  as  that  used  by  practically  all  of 
the  steel  wire  manufacturers  of  the  United  States,  under  various 
names.  It  results  from  this  fact  that  there  is  really  a  standard 
steel  wire  gage  in  the  United  States,  although  this  has  not  been 
formally  recognized. 

"Upon  the  recommendation  of  the  Bureau  of  Standards  at 
Washington,  a  number  of  the  principal  wire  manufacturers  and 
important  consumers  have  agreed  that  it  would  be  well  to  desig- 
nate this  gage  as  the  Steel  Wire  Gage  ;  in  cases  where  it  becomes 
necessary  to  distinguish  it  from  the  British  Standard  Wire  Gage, 
it  may  be  called  the  United  States  Steel  Wire  Gage.  The  name 
thus  adopted  has  official  sanction,  although  without  legal  effect. 

"The  only  wire  gage  which  has  been  recognized  in  Acts  of 
Congress  is  the  Birmingham  gage.  The  Treasury  Department 
has  for  many  years  used  this  gage  in  connection  with  importations 
of  wire,  and  the  adoption  of  succeeding  tariff  acts  with  provisions 
for  the  assessment  of  duty  according  to  gage  numbers  gives 
legislative  sanction  to  the  gage. 
186 


GAGE  187 

"Until  certain  provisions  of  the  tariff  act  are  amended,  the 
Treasury  Department  probably  cannot  discontinue  the  use  of  the 
Birmingham  gage.  It  should,  however,  be  abandoned  by  all 
other  users,  since  the  gage  itself  is  radically  defective,  and  it  is 
nearly  obsolete,  both  in  the  United  States  and  in  Great  Britain, 
where  it  originated. 

"For  copper  wires  and  wires  of  other  metals  the  gage  univer- 
sally recognized  in  the  United  States  is  the  American  Wire  Gage, 
also  known  as  the  Brown  &  Sharpe.  No  confusion  need  arise 
between  the  Steel  Wire  Gage  and  the  American  Wire  Gage, 
because  the  fields  covered  by  the  two  gages  are  distinct  and 
definite."  (From  pamphlet  of  the  American  Steel  &  Wire  Co.) 

The  Roebling  gage  is  practically  the  same  as  the  American 
Steel  &  Wire  Company's  gage.  The  Birmingham  gage  is  some- 
times referred  to  as  the  English  standard  wire  gage.  The 
Edison  or  circular  mil  gage  was  devised  by  the  Edison  Company 
to  simplify  calculations  and  the  ordering  of  round  wires  for 
electrical  purposes.  The  mil  (m)  is  0.001*;  the  circular  mil 
(c.m.)  is  the  area  of  a  circle  with  a  diameter  of  i  mil.  The  com- 
parative area  of  a  wire  (or  circle)  in  circular  mils  is  considered 
simply  as  the  square  of  its  diameter  in  mils.  As  the  areas  of 
circles  are  to  each  other  as  the  squares  of  their  diameters,  com- 
parative results  are  thus  secured  without  the  trouble  of  working 

irDz 
out On  the  scale  employed  the  number  multiplied  by  1000 

gives  the  number  of  circular  mils;  thus,  No.  100  is  100,000  c.m., 
and  No.  50  is  50,000  c.m.;  etc.  The  square  root  of  the  number  of 
c.m.  gives  the  diameter  in  mils;  multiplying  by  0.7854  will  give 
the  actual  area  in  square  mils.  There  are  also  in  use  in  this 
country  a  number  of  screw  gages,  nominally  the  same  but  which 
vary  with  different  makers;  and  the  piano  wire  gage,  in  which 
the  numbers  increase  with  the  diameter.  To  test  the  accuracy 
of  the  openings  or  notches  of  a  wire  gage  an  instrument  known  as 
a  fiat  gage  is  provided.  A  micrometer  gage  or  micrometer 
caliper  has  an  opening  regulated  by  a  screw  arrangement  usually 
reading  in  thousandths  of  an  inch  (or  millimeter).  This  is  the 
type,  in  different  sizes,  most  commonly  used  for  measuring 
thickness,  particularly  of  plates  and  similar  material.  A  special 
form  of  plate  gage,  to  measure  them  during  rolling  (while  hot),  is 
provided  with  a  handle  and  is  operated  by  a  spring  and  trigger  to 
obviate  a  too  near  approach  to  the  hot  pieces.  Calipers,  con- 
sisting of  two  curved  arms  pivoted  at  one  end  are  frequently  used 
for  large  objects,  the  dimensions  being  determined  by  measuring 
on  a  scale  the  opening  between  points.  A  transfer  caliper,  used 
where  there  is  an  enlargement,  which  would  prevent  withdrawing 
the  caliper  without  opening  it,  has  a  small  arm  which  can  be 
adjusted  to  show  the  point  at  which  the  caliper  is  set  when  on 
the  object,  so  that,  after  opening  the  arms  for  withdrawal, 
they  may  again  be  closed  to  the  same  point  as  before  and  the 
opening  measured.  There,  are  various  other  forms  specially 
devised  and  named  according  to  the  purpose  for  which  they  are 
used,  such  as  screw  thread  gages,  track  gages,  wheel  gages,  etc. 


i88 


1     *-s 

*O      «—  t  o 
C       Q_i  •*-> 

l/>            IO            IO            t/)            V)                     l^ 

t>-iotM          t^io          N\o          rct-Mi^jooNO                 rot^ 

t*^cy 

O<^Or-rtM           oOOV5r»5MOOOt^iflTl-           MOO> 

w  II 

•.. 

rt 

a 

oooooooooo*        o"oo 

* 

.gS 

(2^. 

r£  n^           OOOOOOOOOO            OOO 

0 

fit 

1 

^*i  "  ' 

SSS5S38&S&     SSS 

M 

W     C 

WM^ 

0)     cj 

MVW 

o: 
|! 

:-«] 

M                                                                       -           «     00       M 

O»OOOv^t^            Oit^O'i-i-iN'tOOTtM            OOM 
OOMOOON            OOi^NOOOOTtNMO            O\00t^ 

^^     O 

•3  .s 

C3       r/i 

CO     <f' 

-M       OJ 

w  3 

i°|s 

o,,«o,»*   g*a:asg«a?i   «?s 

o 

s 

«ll^ 

S\    <u 

5"s-^ 

"SB 

SS-SS.     §^SSS?5S^S     S?S 

H 

«|j 

'goa  °r^  o 

OiOPOOv-OfOO           oOvO^NOOit^OTj-fO           ei     O     Oi 

<3   4)        ^ 

IH 

55       ° 

OOOOOOO           HOtfJ^tiOvOt^oOOsO           Mnr»5 

o   o   o   o   o 

§0    O 
o 

l/i  V)  V)     N 

10  i/>i/)i/>e«r~i/)NtO 

ION  to         10         \f>         t^   1/5    N  t^  o    fi   ro   N    "-"    o 

N     w  »O  IO  r^    to    <N  r>-    1/3   OO     N    *O  POlOt^OvwrO^l/i 

OOONO  fOt^»  ^"MOOVitHOOt^-ViTfM  OOONOOr^t^-\OO 

l^t^OtOtOTfro  rorOMNNwMWMM  MMQOOOOO 

ooooooo    oooooooooo  oooooooo 

fOO^POOOON  POO>O\OONTfOr- 

OvO^-MiOfOH  iDrO^t^irtOsOOfC 

OOOOO\Oi-'(v>>«  \OOOMPOt-O\rtt^O 
COO»-twt-*M          Mtnc^cscsNcororo 

<Or}-NiHOO»ON  O\>ONOO^tOOTtOt^ 

>o-*ooo(nfOfo  NMNNi^MNvoofo 

OOOlONOOrfM  t^tOfOMOOO'OOi'tt^  O«O«OOOOI*5MOlt^ 

OOt^t^r^vO\OO  u^«O»OiOTfTtTj-rOfOP»  NMWiHOOOOO\O\ 

rJ-00  t^fO  H  Nt^M  »flHt~lO  OO  ^t-^-  COIOW't 

OO^ON»OOO*O  >O^ft~  rt-O\rfio«  NVOOOOi-i  i/l  <O     CO    ^~ 

OOOONfOOOOi  Tj-roiOwO\0\wvO«0  OiOOfOO  rfO\««>-i 

o  ?  o  o  c  o  o  ooooooo  ooe  oooooooooo 

Tj-OOOTf  OOOO«Tf>OOOO«00 

OCSrJ-OOOOO  NOOTtdOOOOTffOW  MOOO\OOt^O>O>^^t 

OOt^\O»0'*<<*-rO  PONNNPIMMMMM  HMMOOOOOOO 

OOOOOOO  OOOOOOOOOO  OOOOOOOOOO 

00    t^  >O    «O    ^t    ^t    f«J  rOMWNMi-iiHiHiHM  wOOOOO 

o  o  o   o   o   9  o  o   o   o   o   o   o   o   o   o   o  oooooo 

1/5 


1 90  GAGE  HOLE— GAS  COAL 

Gage  Hole. — See  page  507. 

Gage  Length ;  Gaged  Length.— Of  a  test  piece:  see  page  473. 

Galbraith  Furnace. — See  page  155. 

Gallet  Process.--See  page  118. 

Galvanic  Action. — Same  as  voltaic  action. 

Galvanic  Process  (rare).— Of  galvanizing:  see  page  370. 

Galvanized  Wire.— See  page  508.  , 

Galvanizing. — See  pages  370  and  431. 

Galvanizing  Pan. — See  page  509. 

Galvanizing  Pot.— See  page  431. 

Galvanometric  Method. — For  temperature  measurements:  see 
page  208. 

Galy-Cazalet  Process. — (i)  For  fluid  compression:  see  page  63; 
(2)  for  steel:  see  page  318. 

Gamma  Cementite.— See  page  273. 

Gamma  (7)  Iron.— See  pages  264  and  272. 

Gamma  Iron  Theory. — Of  hardening:  see  page  280. 

Gamma  Martensite.— See  page  276. 

Gamma  Theory. — Of  hardening:  see  page  280. 

Gangue. — (i)  General:  see  Ore;  (2)  nature  of,  in  iron  ore:  seepage 
243- 

Ganister. — See  page  395. 

Gantry  Crane. — See  page  32. 

Garnaut  and  Siegfield  Process. — See  page  233. 

Gamier  Process. — See  page  385. 

Garrett  Mill.— See  page  417. 

Gartsherrie  Process. — Same  as  Alexander  and  M'Cosh  process; 
for  the  recovery  of  tar  and  ammonia  from  the  gas  of  a  blast  fur- 
nace using  raw  coal. 

Garut  Process. — See  page  503. 

Gas. — Matter  in  a  state  where  the  molecules  are  free  to  move  except 
for  any  external  restraint.  A  perfect  or  ideal  gas  is  one  which 
conforms  to  the  characteristic  equation  of  a  gas: 

pv  =  RT 
p  and  v  are  respectively  the  pressure  and  the  volume  at  the 

given  temperature;   T  is  the  absolute  temperature;  R  is  -^^- 

(for  centigrade  degrees)  or     °  °  (for  Fahrenheit  degrees)  where 
409 

po  and  ED  are  values  at  absolute  zero  for  pressure  and  volume 
respectively.  Boyle's  law  (also  called  Mariotte's  law),  which 
is  not  entirely  true,  is  that  the  volume  of  a  gas  varies  inversely 
as  the  pressure,  the  temperature  remaining  constant.  The 
law  of  Charles  (also  called  after  Dalton  and  Gay-Lussac)  is  that 
the  volume  of  a  gas  varies  directly  with  the  absolute  temperature, 
the  pressure  remaining  constant.  Van  der  Waal's  formula 
expresses  Boyle's  law  with  the  additional  factor  of  molecular 
attraction.  Graham's  law  states  that  the  rate  of  flow  of  a  gas 
is  inversely  proportional  to  the  square  root  of  its  density. 

Gas  Cleaning. — See  page  33. 

Gas  Coal. — See  Coal. 


GAS  COKE— GIT  191 

Gas  Coke. — See  page  97. 

Gas  Collector. — See  page  61. 

Gas  Furnace. — See  page  181. 

Gas  Generating  Furnace ;  Generator. — See  page  362. 

Gas  Hammer. — See  Hammer. 

Gas  Hole. — See  page  55. 

Gas-house  Coke. — See  page  97. 

Gas  Producer. — See  Producer. 

Gas  Pyrometer. — See  page  207. 

Gas  Thermometer. — See  page  205. 

Gas  Washer. — See  page  33. 

Gas  Waste  Acid. — Sulphurous  acid,  SO2;  made  from  spent  oxide 

(oxide  of  manganese  containing  sulphur)  from  the  purifiers  in  gas 

works;  it  contains  no  arsenic. 
Gaseous  Cements. — See  pages  67  and  69. 
Gaseous  State. — See  page  81. 
Gaseous  Volumes. — Law  of:  see  page  85. 
Gasogene  (French).— Gas  producer. 

Gasometer. — A  vessel  or  tank  for  holding  or  measuring  gases. 
Gasparin's  Pyrometer. — See  page  207. 
Gassed. — Of  a  person  overcome  by  gas  at  a  blast  furnace. 
Gate. — See  page  299. 
Gathmann  Process. — See  page  60. 
Gauge. — See  Gage. 
Gay-Lussac's  Law. — See  page  85. 
Gayley  Dry-blast  Process. — See  page  30. 
Gear  Driven. — See  page  407. 
General  Purposes  Temper.— See  Temper. 
General  Selective  Corrosion. — See  page  106. 
Generator ;  Generator  Gas. — See  page  362. 
Gentle  Aeration.— See  page  107. 
Geode. — See  page  125. 
Gerhardt  Process. — See  page  141 
German  Bloomary. — See  page  141. 
German  Clay. — See  page  302. 
German  Dinas  Brick. — See  page  395. 
German  Forge. — See  page  383. 
German  Forge  Hammer. — See  Hammer. 
German  Mill.— See  page  417. 
German  Process.— See  page  75. 
German  Steel  (obs.). — (i)  Steel  (wrought  iron)  made  either  direct 

from  the  ore  (see  page  141)  or  first  into  pig  (see  page  75);  (2) 

cemented  iron:  see  page  71;  (3)  an  old  name  for  shear  steel,  q.v. 
Gerstner's  Law. — See  page  334. 
Gesner  Process.— See  page  369. 
Ghost ;  Ghost  Line ;  Ghost  Structure.— See  page  289. 
Gilchrist  (P.C.)  Process.— See  page  318. 
Gill  (Chas.)  Method. — Of  quenching:  see  page  229. 
Gillon  and  Dujardin  Mill.— See  page  417. 
Gin  Furnace. — See  page  155. 
Girod  Furnace.— See  page  156. 
Git ;  Git  Mold. — See  pages  61  and  299. 


IQ2  GJERS  METHOD— GRAM-MOLECULAR 

Gjers  Method. — For  mixing  steel:  by  pouring  it  from  one  ladle  into 
another. 

Gjers  Pit. — See  page  184. 
-  Glance  Coal. — See  Coal. 

Glanced  Sheet. — See  page  431. 

Glass  Hardness.— See  Hardness. 

Glaze. — See  page  370. 

Glazed  Bars. — See  page  71. 

Glazed  Pig ;  Glazy  Iron.— See  page  343. 

Glide  Plane  ;  Gliding  Plane.— See  pages  123  and  282. 

Globular  Pearlite. — See  page  2  74. 

Globulite. — See  page  120. 

Glut  Weld.— See  page  502. 

Gnathoid. — See  page  290. 

Gobbed  Heat— See  page  377. 

Gobbing  Up.— See  page  35. 

Goethite. — See  page  244. 

Goldschmidt  Process. — A  method  for  producing  metals  by  reduc- 
tion with  aluminum.  The  ore  or  oxide  of  the  metal  and  metallic 
aluminum,  both  in  a  finely  granular  condition,  are  mixed  together 
(this  mixture  is  called  thermit),  and  the  reaction  started  by  ignit- 
ing a  small  quantity  of  magnesium  powder  or  ribbon,  etc.,  called 
the  starter,  placed  on  top  of  the  charge.  The  reaction  then  pro- 
ceeds with  considerable  violence  and  the  resulting  metal  is  at  a 
high  temperature.  The  process  is  used  for  obtaining  carbonless 
metals  and  alloys;  the  metal,  on  account  of  its  high  temperature 
is  also  employed  for  repairing  broken  pieces  of  machinery,  and 
the  hot  slag  produced  is  also  used  for  heating  the  ends  of  tubes, 
etc.,  which  are  to  be  welded  together. 

Goniometer. — See  page  119. 

Gore's  Phenomenon.— See  page  265. 

Gossan. — See  page  245. 

Gothic  Pass ;  Groove.— See  page  405. 

Gozzan.— See  page  245. 

Grade. — Of  steel:  see  page  455. 

Gradual  Cement.— See  page  67. 

Graduated. — Of  a  measuring  tube  or  vessel  which  is  marked  off  with 
fine  lines  to  show  proportional  volumes;  such  a  vessel  is  called 
a  graduate. 

Graff  Process.— See  page  141. 

Graham's  Law.— See  Gas. 

Grain. — See  page  122. 

Grain  of  First  Order.— See  page  127. 

Grain  Growth. — (i)General:  see  page  213;  (2)  as  affected  by  strain: 
see  page  216. 

Grain  Refining. — See  pages  212  and  232. 

Grain  Roll.— See  page  403. 

Grain  of  Second  Order. — See  page  127. 

Grain  Size. — See  page  213. 

Gram  Calorie.— See  page  199. 

Gram-centigrade  Heat  Unit. — See  page  199. 

Gram-molecular  Volume.— See  page  83. 


GRAM-MOLECULAR—GREGORY  1 93 

Gram-molecular  Weight. — See  page  83. 

Grampus. — See  page  135. 

Granitoid  Structure. — See  page  125. 

Granular. — See  page  122. 

Granular -crystalline  Fracture. — See  page  1 78. 

Granular  Eutectic. — See  page  269. 

Granular  Fracture. — See  page  1 78. 

Granular  Iron. — Bar  (wrought)  iron  which  shows  a  granular  frac- 
ture due  to  the  absence  of  cinder,  and  is"  therefore  a  guarantee  of  its 
strength  and  purity  (Horner). 

Granular  Pearlite. — See  page  274. 

Granulated  Iron. — Pig  iron  reduced  to  the  size  of  shot  by  pouring 
the  molten  metal  into  water. 

Granulation. — See  page  121. 

Granulation  Range  ;  Zone. — See  page  121. 

Granule;  GranuUtic. — See  page  122. 

Granulitic  Structure. — See  page  125. 

Graph. — See  Curve. 

Graphic  Formula. — See  page  86. 

Graphite. — (i)  Form  of  carbon:  see  page  50;  (2)  constituent  of 
iron:  see  page  277;  (3)  a  refractory:  see  page  398. 

Graphite  Blacking. — See  page  298. 

Graphite  Crucible. — See  page  in. 

Graphitic  Carbon. — See  Graphite. 

Graphitic  Corrosion. — See  page  106. 

Graphitic  Pig.— See  page  342. 

Graphitic  Silicon. — See  Silicon. 

Graphitiferous.— Containing    graphite. 

Graphitite.— See  Carbon. 

Sraphitization.— See  pages  106  and  278. 

Graphitization  of  Cementite. — See  page  278. 

Graphitoid  ;  Graphitoidal. — See  Carbon. 

Graphitoidal  Pig  Iron. — Graphitic  pig  iron;  in  which  practically  all 
the  carbon  is  in  the  graphitic  form. 

Graphitoidal  Silicon. — See  Silicon. 

Grate  Bars. — The  bars  across  a  fireplace  which  support  the  fuel. 

Gray  Body.— See  page  207. 

Gray  Cast  Iron ;  Forge  Iron.— See  page  342. 

Gray-granular  Fracture.— See  page  178. 

Gray  Iron  ;  Pig.— See  page  342. 

Grease  Pan ;  Pot.— See  page  432. 

Greater  Calorie. — See  page  199. 

Greatest  Principal  Stress. — See  page  332. 

Green. — Unused  or  raw;  untreated  or  incompletely  treated. 

Green  Brick.— See  page  395. 

Green  Coal.— See  Coal. 

Green  Fire.— See  page  203. 

Green  Ingot. — See  page  57. 

Green  Sand ;  Green  Sand  Molding. — See  page  296. 

Green  Vitriol. — Commercial  sulphate  of  iron. 

Greenawalt  Process. — See  page  45. 

Gregory  and  Green  Process. — See  page  386. 

13 


1 94  GRENET'S  SERIES— GUTTER 

Grenet's  Series  of  Salts.— To  determine  temperatures:  see  page 
209. 

Grey  Mill. — See  page  417. 

Gridiron  Twinning. — See  page  124. 

Grinding. — (i)  Preparing  smooth  surfaces  by  abrasion;  (2)  reduc- 
ing a  substance  to  a  fine  state  of  division. 

Grips. — Of  a  testing  machine:  see  page  469. 

Gripper. — In  wire  drawing:  see  page  508. 

Grog  (Eng.)  —  See  page  396. 

Grb'ndal  Furnace. — See  page  156. 

Grondal-Kjellin  Furnace. — See  page  156. 

Grondal  Process. — See  page  44. 

Gronwall  Furnace. — See  page  157. 

Gronwall,  Lindblad  and  Stalhane  Furnace. — See  page  157. 

Groove ;  Grooved  Roll. — See  page  404. 

Gross  Ton.— See  Ton. 

Ground  Mass. — See  page  125. 

Group  Casting. — See  pages  61  and  299. 

Growth  of  Crystals. — See  pages  120  and  213. 

Grundy. — Granulated  pig  iron  (Raymond). 

Gruson's  Chilled  Cast  Iron  Armor. — See  page  9. 
•  Guard. — See  page  415. 

Guard  Plate. — See  page  32. 

Gubbin. — A  kind  of  ironstone  (Raymond). 

Guenyveau  Process. — See  page  380. 

Guest  Process. — See  page  380. 

Guide  ;  Guide  Mill ;  Guide  Roll. — See  page  415. 

Guillaume's  Invar. — See  page  451. 

Guillery's  Method. — For  determining  hardness:  see  page  478. 

Guillef  s  Theory.— (i)  Of  hardening:  see  page  280;  (2)  of  ternary 
steels:  see  page  443. 

Guillotine  Shears. — See  page  412. 

Guit. — See  page  299. 

Gun. — For  a  blast  furnace:  see  page  37. 

Gun  Iron ;  Metal. — See  page  343. 

Gun  Screw  Wire. — See  page  509. 

Gunther  Process. — See  page  141. 

Gurlt  Process. — See  page  141. 

Gusy  (Eng.).— Of  steel,  wild. 

Guthrie's  Cryohydrate. — See  page  266. 

Gutowsky's  Diagram. — See  page  272. 

Gutter. — (i)  Spout;  (2)  the  name  sometimes  given  to  the  runner  of 
a  blast  furnace. 


H 

H. — Chemical  symbol  for  hydrogen,  q.v. 

He. — Chemical  symbol  for  helium:  see  page  84. 

Hg. — Chemical  symbol  for  mercury  (Latin,  hydrargyrum) :  see  page 
84. 

Ho. — Chemical  symbol  for  holmium:  see  page  84. 

H.J. — Hot  junction  (of  a  couple):  see  page  209. 

H.R.P.  &  L. — Hot  rolled,  pickled  and  limed  (of  strips,  bars,  etc.). 

Hackly  Fracture. — See  page  1 78. 

Had  field's  Manganese  Steel. — See  page  451. 

Hadfield  Process. — (i)  For  reduction:  heating  the  oxide  of  a  metal 
with  granulated  aluminum  and  a  little  fluorspar  in  a  crucible; 
(2)  for  sound  ingots:  see  page  60. 

Haematite  (Eng1.). — Hematite,  q.v. 

Hainsworth  Process. — See  page  60. 

Hair  Crack. — See  Seam. 

Hair  Plate. — See  page  135. 

Hair  Seam. — See  Seam. 

Halberger  Furnace. — See  page  158. 

Half-chamotte  Brick. — See  page  396. 

Half-cup  Fracture. — See  page  179. 

Half  Roll. — See  page  404. 

Half-silica  Brick. — See  page  396. 

Hammer. — Of  a  drop  test  machine:  see  page  481. 

Hammer. — A  device  for  forging  or  reducing  the  section  of  a  piece 
of -metal,  or  changing  the  shape,  consisting  essentially  of  a  mass 
of  metal,  the  hammer  proper  (hammer  head  or  tup),  which  falls 
.or  is  driven  violently  against  the  piece  to  be  acted  upon.  The 
face  of  the  hammer  is  usually  removable  and  is  called  the  hammer 
block  or  die  (particularly  the  latter  if  of  a  special  section;  this 
also  applies  to  the  anvil  block).  The  piece  is  supported  on  a 
heavy  mass  of  metal,  the  anvil,  generally  of  cast  iron  or  steel,  to 
render  the  blow  effective.  If  the  face  is  removable  it  is  called  the 
anvil  block.  A  working  anvil  block  (Eng.)  is  a  block  of  steel  or 
cast  iron  fitting  on  the  top  of  the  anvil  block.  A  false-block  is 
usually  a  casting  inserted  between  the.  anvil  block  and  the  bottom 
die  of  a  steam  hammer  to  raise  the  die  to  the  proper  height.  A 
projecting  dovetail  on  the  lower  face  of  the  false-block  is  keyed 
into  a  recess  in  the  anvil  block,  while  a  recess  on  its  top  face 
receives  the  dovetail  projecting  from  the  bottom  surface  of  the 
bottom  die.  Its  only  purpose  is  to  save  weight  in  the  bottom  die. 
When  this  is  to  be  changed  often,  as  in  shape  or  swage  work,  it 
is  undesirable  to  have  it  as  heavy  and  cumbersome  as  would  be 
necessary  were  the  die  keyed  directly  into  the  anvil  block  (G. 
Aertsen).  Hammers  light  enough  are  worked  by  hand  (hand 
hammer,  sledge),  but  those  of  any  considerable  weight  are  oper- 
ated by  power,  usually  steam,  rarely  water.  They  may  be  classi- 
fied according  to  the  source  of  power,  into: 


196 


HAMMER 


I.  Water: 

i.  Indirect:  Helve. 

II.  Steam: 

1.  Indirect:  Helve. 

2.  Direct:  Ordinary  steam  hammer: 

(a)  Single-acting. 

(b)  Double-acting. 

III.  Gas:  Direct. 

Steam  hammers  consist  of  an  anvil,  and  the  hammer  proper 
fastened  to  one  end  of  a  rod,  the  other  end  being  connected  to  a 
piston  which  travels  in  a  steam  cylinder.  If  steam  is  admitted 
to  only  one  side  of  the  piston,  simply  to  raise  the  hammer  which 
falls  by  gravity,  it  is  single-acting  ;  if  steam  is  also  used  to  drive 
the  hammer  down  and  so  increase  the  force  of  the  blow,  double- 
acting.  In  either  case  the  hammer  is  always  rated  according  to 


FIG.  23. — Steam  hammer. 
(Thurston,  "Iron  and  Steel.") 

the  weight  of  the  tup.  A  helve  (crocodile  hammer,  lift  hammer, 
tilt  hammer,  trip  hammer,  fly  hammer,  German  forge  hammer) 

is  a  hammer  operated  on  the  principle  of  a  lever,  the  tup  falling 
by  gravity.  The  tup  is  attached  to  a  bar  or  handle  of  wood  or 
iron,  working  on  a  pivot  or  fulcrum.  The  actuating  mechanism 
consists  of  a  wheel  or  shaft  driven  by  water  (water  helve,  battery) 
or  by  steam  (steam  helve),  provided  with  cams  or  teeth.  De- 


HAMMER— HARD  SPOTS  197 

pending  upon  the  general  arrangement,  various  names  are  as- 
signed: If  the  power  is  applied  at  one  end,  the  pivot  being  at 
the  other,  and  the  tup  intermediate,  it  is  called  a  nose  helve, 
frontal  helve,  or  T  hammer;  if  the  force  acts  in  the  middle,  a 
belly  helve ;  while  if  the  pivot  is  in  the  middle,  a  tail  helve. 
When  not  in  use  the  helve  is  supported  by  a  wooden  prop  or  gag. 
A  drop  hammer  is  one  which  is  allowed  to  fall  by  gravity,  being 
attached  to  a  belt  which  passes  over  a  pulley  supplying  the 
necessary  power  for  raising  it.  A  cogging  hammer  is  one  used  for 
reducing  ingots  to  blooms.  A  plating  hammer  (obs.)  was  for- 
merly used  in  the  manufacture  of  plates  or  sheets.  A  gas  ham- 
mer is  operated  on  the  same  principle  as  a  gas  engine.  A  raising 
hammer  (Eng.)  is  a  term  sometimes  employed  for  a  hammer  used 
for  forming  or  cupping  sheets,  having  a  long  rounded  head.  See 
also  Forging. 

Hammer  Block. — See  Hammer. 

Hammer  Dressing. — See  Forging. 

Hammer  Forging. — See  Forging. 

Hammer  Hardness. — See  Hardness. 

Hammer  Head.-^See  Hammer. 

Hammer  Refining. — See  Mechanical  Refining. 

Hammer  Scale. — See  Scale. 

Hammer  Slag.— See  Slag. 

Hammer  Test. — See  page  476. 

Hammered  Weld. — See  page  501. 

Hamoir  Process. — See  page  386. 

Hampton  Process. — See  page  9. 

Hand  Guide  Mill. — See  page  416. 

Hand  Hammer. — See  Hammer. 

Hand  Mill. — See  page  416. 

Hanging. — Of  a  blast  furnace:  see  page  35. 

Hanging  Guard. — See  page  415. 

Hanging  Test. — See  page  469. 

Hank.— See  Coil. 

Hannover  Process. — See  Alloy. 

Harbord  Process. — See  page  30. 

Hards.— See  Slag. 

Hard  Blow. — See  page  21. 

Hard  Castings. — Malleable  castings:  see  page  257. 

Hard  Center. — The  effect  produced  usually  by  too  rapid  heating,  so 
that  the  inside  of  a  piece  of  metal  is  insufficiently  heated,  and 
consequently  is  worked  at  too  low  a  temperature;  rarely  caused 
by  segregation. 

Hard-centered  Steel. — See  page  64. 

Hard  Coal.— See  Coal. 

Hard  Solder. — See  page  505. 

Hard  Spots. — Spots  or  streaks  in  steel  which  are  harder  than  the 
body  of  the  metal.  This  is  generally  observed  when  material  is 
machined.  They  are  of  infrequent  occurrence  and  may  be  due 
to  segregation  (segregated  spot)  or  to  imperfect  mixing  of  the 
manganese  addition  (manganese  spot).  Soft  spots  are  just  the 


1 98  HARD  STEEL— HARDNESS  TESTS 

opposite,  due  to  absence  of  carbon  and  manganese,  probably  on 
account  of  some  local  oxidizing  action. 

Hard  Steel. — See  page  455. 

Hard  Tap. — In  tapping  a  furnace,  when  the  tapping  hole  is  opened 
up  only  with  difficulty. 

Hardened  Castings  (rare). — See  page  58. 

Hardener. — The  name  sometimes  used  for  foundry  iron  high  in 
manganese,  or  for  the  manganese  itself. 

Hardening. — Bringing  material  to  the  condition  in  which  it  is  best 
able  to  resist  indentation,  abrasion  or  scratching.  There  are  two 
general  methods  for  accomplishing  this:  (a)  heating  to  a  suffi- 
ciently high  temperature  and  then  cooling  rapidly  (this  applies 
only  to  steel  or  iron  alloys:  see  Heat  Treatment),  and  (b)  by 
cold  mechanical  working.  The  Dean  process  was  designed  to 
harden  and  strengthen  the  bore  of  guns,  etc.  It  consisted  in 
forcing  through  them  a  succession  of  tapered  steel  cylinders,  each 
slightly  larger  than  the  preceding.  It  was  stated  to  have  been 
used  successfully  for  bronze  guns,  but  that  it  did  not  diminish  the 
erosion  of  steel  guns. 

Hardening  Carbide.— See  page  276. 

Hardening  Carbon.— See  pages  276  and  278. 

Hardening  Carbon  Theory. — Of  hardening:  see  page  280. 

Hardening  Effect. — Of  permanent  set:  see  page  334. 

Hardening  on  a  Falling  Heat. — See  page  229. 

Hardening  Phosphorus. — See  Phosphorus. 

Hardening  Quenching. — See  page  228. 

Hardening  by  Reheating. — See  page  279. 

Hardening  on  a  Rising  Heat. — See  page  228. 

Hardening,  Special  Methods  of. — See  page  229. 

Hardening  by  Subcooling. — See  page  279. 

Hardening  Theories. — See  pages  279  and  280. 

Hardening  by  Overstraining. — See  page  279. 

Hardenite. — (i)  Constituent  of  steel:  see  page  275;  (2)  Caron's 
cement:  see  page  68. 

Hardite.— See  page  278. 

Hardness. — The  resistance  offered  by  a  body  to  abrasion  or  pene- 
tration. (For  methods  for  determining  relative  hardness,  see 
Testing.)  The  hardness  of  steel  is  sometimes  called  its  temper, 
and  to  draw  the  temper  means  to  anneal.  Natural  hardness  is 
the  hardness  of  material  as  ordinarily  made,  without  any  special 
additional  treatment.  -  Glass  hardness  is  the  highest  degree  of 
hardness  attainable  by  steel,  in  which  condition  it  can  scratch 
glass;  but  as  the  hardness  of  glass  may  vary,  it  has  been  suggested 
that  flint  hardness  be  substituted.  Hammer  hardness  (or 
rolling  hardness)  is  the  effect  produced  when  heated  metal  is 
worked  below  its  critical  temperature;  if  this  reaches  a  tempera- 
ture corresponding  to  a  blue  temper  color  (blue  working),  the 
metal  may  be  rendered  brittle,  in  this  case  called  blue -shortness : 
see  also  page  331. 

Hardness  Number. — See  page  477. 

Hardness  Tests.— See  page  477. 


HARMET  PROCESS— HEAT  1 99 

Harmet  Process. — (i)  Fluid  compression:  see  page  64;  (2)  electric 
furnace:  see  page  158;  (3)  basic  Bessemer:  see  page  21. 

Harvey  Process. — (i)  Carburizing:  see  page  9;  (2)  direct:  see 
page  141. 

Hatton  Converter. — See  page  24. 

Hawkins  Process. — See  page  141. 

Hay  Band  ;  Rope. — See  page  299. 

Haythorne  Process. — See  page  385. 

Head  ;  Head  Metal. — See  page  56. 

Head  Squeezer. — See  page  377. 

Header. — See  page  56. 

Healing. — Where  cracks  are  formed  in  an  ingot  during'the  first'few 
passes  in  rolling  it  down,  which  are  later  welded  up  if  the  tempera- 
ture is  high  enough  and  the  metal  is  sufficiently  soft  (low  in 
carbon). 

Heap.— See  page  181. 

Heart. — Core:  see  page  67. 

Hearth. — (i)  Of  a  blastfurnace:  see  page  27;  (2)  charcoal  hearth: 
see  page  75;  (3)  furnace:  seepage  182;  (4)  of  an  open  hearth  fur- 
nace: see  page  310. 

Hearth  Fining  ;  Refining. — :See  page  382. 

Heat. — A  form  of  energy  (heat  energy)  due  to  molecular  motion 
(dynamic  theory  of  heat.)  It  was  at  one  time  believed  that  heat 
was  an  actual  substance  called  caloric.  Two  kinds  of  heat  are 
recognized:  sensible  and  latent.  Sensible  heat  or  thermome- 
tric  heat  is  the  degree  of  heat  which  a  body  possesses,  commonly 
known  as  its  temperature.  The  measurement  of  ordinary  or 
relatively  low  temperatures  is  performed  by  instruments  called 
thermometers,  and  of  high  temperatures  by  pyrometers  (see 
below). 

Latent  heat  is  the  amount  liberated  or  absorbed  due  to  an  in- 
ternal or  molecular  change  occurring  in  a  body  at  constant  tem- 
perature. There  are  three  causes  for  this  spontaneous  liberation 
(evolution)  or  absorption  of  heat:  (a)  formation  or  dissociation  of 
chemical  compounds;  (6)  changes  of  state;  (c)  allotropic  or  poly- 
morphic transformations.  The  amount  of  heat  is  measured  in 
heat  units  or  thermal  units  which  are  based  on  either  the  metric 
or  the  English  system.  In  the  metric  system  the  calorie  (some- 
times spelled  calory ;  also  called  kilogram-centigrade  heat  unit, 
large  calorie,  kilogram  calorie,  greater  calorie,  major  calorie, 
French  calorie,  or  true  calorie)  is  the  amount  of  heat  required  to 
raise  i  kg.  of  water  through  i°  C.;  the  zero  calorie  is  where  the 
water  is  raised  from  o°  to  i°  C.;  the  common  calorie  where  the 
water  is  raised  from  15  to  16°  C.;  and  the  mean  calorie  the  one- 
hundredth  part  of  the  amount  of  heat  necessary  to  raise  the 
kilogram  of  water  from  o°  to  100°  C.  The  small  calorie  (gram- 
centigrade  heat  unit,  gram  calorie,  minor  calorie  or  lesser  calorie) 
is  the  heat  required  to  raise  i  gram  of  water  'through  i°  C., 
hence  is  the  one-thousandth  part  of  the  calorie.  The  British 
thermal  unit  (B.T.U.)  is  the  amount  of  heat  required  to  raise 
the^temperature  of  i  Ib.  (avr.)  of  water  through  i°  F.,  usually  at 
ordinary  temperatures  from  say  65  to  66°  F.,  sometimes  from  32° 


200  HEAT 

to  33°  F.  A  hybrid  unit  rarely  employed  is  the  pound  calorie 
(pound-centigrade  heat  unit)  which  is  the  amount  of  heat 
required  to  raise  the  temperature  of  i  Ib.  of  water  through  i°  C. 
For  purposes  of  conversion:  i  cal.  =  3.968  B.T.U.;  i  B.T.U.  = 

0.252  cal.;  i  Ib.  cal.  =— B.T.U.  =  0.4536  cal. 

Heat  may  be  transmitted  in  one  or  more  of  three  ways,  by 

1.  Conduction:  the  heat  traveling  through  a  solid  body  one 
end  of  which  is  connected  directly  with  the  source  of  heat;  molecu- 
lar transference. 

2.  Convection:  by    currents    (transference)    of    the    actual 
particles  of  a  gas  or  liquid. 

3.  Radiation:  by  heat  waves  emanating  from  the  source  of 
heat  and  not  affected  by  the  medium  through  which  they  pass; 
also  termed  radiant  energy  or  radiant  heat.    Thermal  conduc- 
tivity is  used  to  distinguish  it  from  electrical  conductivity,  etc., 
also  for  the  relative  property  of  a  given  body  or  the  amount  of 
heat  passing  through  a  unit  plate  when  the  opposite  sides  have  a 
difference   of   i°  of    temperature;    thermometric    conductivity 
is  the  thermal  conductivity  with  a  unit1  of  "heat  sufficient  to 
raise  a  unit  volume  one  degree"  (Std.  Diet.).     Newton's  law  of 
radiation  (or  of  cooling)  is  that  "the  amount  of  heat  radiated  from 
one  body  to  another  in  a  unit  time  is  a  direct  function  of  the 
difference  in  temperature  of  the  two  bodies."     Emissivity  or 
external  conductivity  is  the  rate  at  which  a  body  radiates  heat. 
Dulong  and  Petit  found  that  the  rate  of  radiation  depended  only 
on  the  nature  of  the  surface  and  on  the  temperature  of  a  body 
and  of  its  surroundings  and  not  on  its  shape;  that  convection 
depended  on  the  temperature  of  a  body  and  of  its  surroundings 
and  upon  its  shape  and  position,  but  not  on  the  nature  of  its 
surface   (Langmuir).    Langmuir's  film  theory  is  that  around 
each  surface  there  is  a  small  volume  of  gas  through  which  heat 
passes  mainly  by  conduction.     The  term  surface  resistance  refers 
to  resistance,  offered  by  the  surface  itself  irrespective  of  the  mate- 
rial, to  loss  of  heat  from  furnaces,  etc.,  while  thermal  resistance 
refers  to  the  material  itself  irrespective  of  the  surface.     A  radia- 
tion curve,  showing  the  rate  of  cooling  of  a  body,  is  the  same  as  a 
cooling  curve.    Prevost's  law,  also  known  as  the  law  of  exchanges, 
is  that  all  bodies  above  absolute  zero  radiate  heat,  the  amount 
being  dependent  only  upon  the  absolute  temperature;  of  two 
adjacent  bodies  at  different  temperatures,  the  one  at  the  lower 
temperature  receives  more  than  it  emits;  if  at  the  same  tempera- 
ture, the  exchange  is  equal  but  does  not  cease. 

A  process  in  which  heat  is  liberated  is  known  as  an  exothermic 
reaction ;  one  in  which  it  is  absorbed,  an  endothermic  reaction. 
A  body  responsible  for  an  exothermic  reaction  is  sometimes  termed 
a  refrigerating  agent  or  refrigerant ;  in  the  case  of  an  endo- 
thermic reaction,  a  calorific  agent.  The  amount  of  heat  liberated 
or  absorbed  when  a  chemical  compound  is  formed  is  called  the 
heat  of  formation.  Hess's  law,  forming  the  foundation  of 
thermo-chemistry,  is  that  in  any  chemical  action  the  amount  of 


HEAT  201 

heat  liberated  is  independent  of  whether  the  action  is  continuous 
or  interrupted.  The  law  of  constant  heat  sums  is  that  in  any 
chemical  change  the  amount  of  heat  is  not  dependent  on  the 
order  or  nature  of  changes,  but  only  on  the  final  result.  The 
law  of  thermoneutrality  is  that  if  dilute  solutions  of  neutral  salts 
are  mixed  and  no  precipitation  occurs,  no  thermal  change  is 
involved. 

Calorimetry  is  the  determination  of  the  total  heat  units  in  a 
body  or  involved  in  a  given  reaction  or  transformation.  The 
measurement  of  heat  liberated  or  absorbed  is  determined  by 
means  of  an  instrument  called  a  calorimeter,  in  which  the  given 
determination  is  made,  e.g.,  when  fuel  is  burned  (heat  of  combus- 
tion), the  value  being  usually  obtained  from  the  increase  or 
decrease  in  the  temperature  of  a  definite  weight  of  water.  Calo- 
rimeters on  this  principle  have  been  devised  by  Berthelot, 
Siemens,  and  White.  Specific  heat  (thermal  capacity)  is  the 
ratio  between  the  amounts  of  heat  required  to  raise  the  tempera- 
ture of  a  unit  weight  of  a  substance  and  of  water  i  degree  (either 
Centigrade  or  Fahrenheit).  This  may  be  determined  for  a  given 
substance  by  mixing  a  known  weight  at  a  certain  temperature 
with  a  known  weight  of  water  at  a  different  temperature  and 
calculating  from  the  temperature  of  the  mixture;  this  is  called 
the  method  of  mixtures.  If  the  mixture  evolves  heat  (as  when 
sulphuric  acid  and  water  are  mixed)  this  method  cannot  be  used, 
but  the  result  may  be  secured  by  the  method  of  cooling  which 
consists  in  comparing  the  time  required  for  cooling  of  the  same 
weights  of  water  and  of  the  substance  through  the  same  range 
of  temperature  under  identical  conditions.  The  water  equiva- 
lent of  a  substance  is  its  weight  multiplied  by  it's  specific  heat. 
The  molecular  heat  of  a  substance  is  its  specific  heat  multiplied 
by  its  molecular  weight.  The  heat  weight  is  the  amount  of  heat 
in  a  body  divided  by  its  absolute  temperature.  The  heat  of 
solution  is  the  amount  of  heat,  either  positive  or  negative  respec- 
tively, when  heat  is  liberated  or  absorbed  when  a  body  goes  into 
solution.  When  an  acid  is  neutralized  by  an  equivalent  weight 
of  a  base,  or  vice  versa,  the  heat  liberated  is  called  the  heat  of 
neutralization.  The  heat  of  ionization  is  the  difference  in  the 
amount  of  heat  when  the  body  is  undissociated  (neutral)  and 
when  ionized. 

Fusion  or  melting  is  the  conversion  of  a  solid  into  a  liquid. 
The  water  of  crystallization  of  certain  salts  may  be  sufficient 
to  dissolve  them  when  heated;  this  is  really  a  case  of  solution, 
but  is  sometimes  termed  aqueous,  aqueo -igneous,  hydrothermal, 
or  watery  fusion ;  true  fusion,  where  heat  alone  is  responsible 
for  the  change  of  state,  is  then  termed  igneous  or  dry  fusion. 
The  heat  absorbed  in  the  conversion  is  called  the  heat  of  fusion 
or  more  specifically  the  latent  heat  of  fusion.  The  temperature 
at  which  this  change  occurs  is  the  fusion  point  or  melting  point 
(on  cooling,  the  freezing  or  solidification  point).  If  there  is  no 
well-defined  temperature,  the  change  extending  over  a  range,  it 
is  sometimes  known  as  vitreous  fusion.  A  fused  substance  above 
(usually  considerably  above)  its  melting  point  is  sometimes 


202  HEAT 

referred  to  as  supermolten.  If  under  given  conditions  of  tem- 
perature and  pressure  a  body  may  exist  simultaneously  as  a  liquid 
and  a  gas,  the  latter  is  termed  a  vapor  and  its  formation  from  the 
exposed  surface  of  the  liquid  is  called  evaporation  or  vaporization  ; 
the  heat  absorbed  in  the  process  is  the  heat  of  vaporization  or 
latent  heat  of  vaporization  ;  if  under  the  given  conditions  no  more 
vapor  can  be  formed  it  is  said  to  be  saturated.  If  the  evolution  of 
the  vapor  occurs  throughout  the  liquid,  thereby  stirring  it  up  and 
disturbing  the  surface,  the  process  is  called  ebullition  or  boiling, 
and  the  minimum  temperature  at  which  this  can  occur,  the  boil- 
ing point.  The  heat  consumed  in  changing  a  liquid  into  a  vapor  is 
converted  into  two  kinds  of  energy;  that  which  causes  a  separa- 
tion of  the  particles  (heat  of  disgregation,  and  that  which  over- 
comes the  external  pressure-  in  increasing  the  volume  (heat  of 
expansion).  The  total  heat  (sensible  plus  latent)  is  that  required 
to  bring  a  liquid  from  the  melting  point  and  change  it  into 
saturated  vapor.  Superheating,  as  a  general  term,  signifies 
heating  above  a  critical  point,  e.g.,  superheated  steam  is  steam 
heated  above  the  point  of  vaporization  (the  boiling  point). 
Where  a  liquid  is  converted  by  heat  into  vapor  which  is  led  into 
another  cold  vessel  and  there  condensed,  the  process  is  termed 
distillation ;  where  a  solid  changes  into  a  vapor  (and  back  again 
into  a  solid)  without  passing  through  an  intermediate  liquid  state, 
the  process  is  termed  sublimation. 

Combustion  is  oxidation  accompanied  by  the  evolution  of 
light  and  heat.  In  its  commonly  accepted  sense,  it  is  the  oxida- 
tion or  burning  of  carbon  and  hydrogen,  either  free  or  combined; 
it  is  also  applied  at  times  to  the  oxidation  of  impurities  or  con- 
stituents in  some  refining  process.  Ignition  is  frequently  used 
in  the  same  sense  as  combustion;  it  is  also  employed  to  indicate 
heating  to  incandescence,  resulting  also  in  the  burning  and  driv- 
ing off  of  any  combustible  and  volatile  matter,  as  in  the  case  of 
chemical  precipitates.  Before  combustion  can  take  place, 
each  fuel  must  be  heated  to  a  certain  definite  temperature  known 
as  its  ignition  point,  and,  depending  upon  whether  the  tempera- 
ture of  combustion  does  or  does  not  exceed  this,  it  is  continuous, 
or  non-continuous  (discontinuous)  combustion.  In  the  case  of 
liquid  fuels  (oils),  a  combustible  vapor  is  given  off  at  a  tempera- 
ture below  the  ignition  point,  and  this  temperature  is  called  the 
flash  point.  If  the  action  is  very  feeble,  the  combustion  is  said  to 
be  slow  or  incipient ;  while  if  energetic,  it  is  called  rapid  or  active. 
Spontaneous  combustion  is  the  result  of  oxidation  of  a  substance 
by  the  air  at  ordinary  temperatures,  where  the  heat  is  not  removed 
as  rapidly  as  formed,  so  that  finally  the  temperature  of  the 
substance  reaches  the  ignition  point.  The  products  of  com- 
bustion (waste  gases  or  fire  gases)  are  the  gases  resulting  when 
a  fuel  is  burned,  and  do  not  include  any  solid  residue  or  ashes. 
When  the  waste  gases  and  the  ashes  contain  no  combustible 
substance,  the  combustion  is  complete ;  otherwise  incomplete. 
Retarded  combustion,  as  in  the  manufacture  of  producer  gas,  is  a 
case  of  incomplete  combustion.  Smoke  is  produced  when  the 
waste  gases  contain  fine  particles  of  unconsumed  carbonaceous 


HEAT  203 

matter  as  a  result  of  incomplete  combustion;  a  green  fire  is  one 
which  is  smoky  hence  has  a  tendency  to  be  reducing.  Flame  js 
the  phenomenon  occurring  when  combustible  gases  are  formed 
during  combustion,  and  the  luminosity  depends  upon  the  tem- 
perature of  the  flame,  the  density  of  the  gases,  and  the  presence 
of  solid  incandescent  particles,  principally  the  last.  Dulong's 
law  for  carbonaceous  and  hydro-carbonaceous  fuels,  which  is 
only  approximately  correct,  is  that  the  heat  generated  in  their 
combustion  is  equal  to  the  sums  of  the  heat  of  the  carbon  and 
hydrogen  separately,  less  an  amount  of  the  latter  element  in  the 
proportion  necessary  to  form  water  with  any  oxygen  present. 

C.  P.  =  8o8oC  +  34,462(H-^) 

C.  P.  =  calorific  power  in  calories;  C,  H,  and  O  the  weights  in 
kilograms  respectively  of  carbon,  hydrogen,  and  oxygen. 

"If  an  explosive  gaseous  mixture  is  either  ignited  on  or  forced 
through  the  interstices  of  a  porous,  refractory,  incandescent  solid 
.  under  certain  conditions,  a  greatly  accelerated  combustion  takes 
place  within  the  interstices  or  pores,  or  in  other  words,  within 
the  boundary  layers  between  the  gaseous  and  solid  phases 
whenever  these  may  be  in  contact — and  the  heat  developed  by 
this  intensified  combustion  maintains  the  surface  in  a  state  of  in- 
candescence without  any  development  of  flame.  Such  conditions 
realize  my  conception  of  flameless,  incandescent,  surface  com- 
bustion as  a  means  of  greatly  increasing  the  general  efficiency  of 
industrial  heating  operations  whenever  it  can  be  conveniently 
applied."  (W.  A.  Bone,  abs.  in  Iron  Age,  Dec.  7,  1911,  1248+.) 

The  amount  of  heat  (number  of  heat  units)  produced  when  a 
unit  weight  of  a  substance  burns  is  called  the  calorific  power 
(C.  P.)  or  heat  of  combustion  and  always  has  the  same  value  irre- 
spective of  the  rate  of  combustion  (i.e.,  the  time  occupied).  •  The 
resulting  temperature  is  called  the  calorific  intensity  (C.  I.)  or 
pyrometer  effect  (rare),  or  temperature  of  combustion,  which 
varies  according  to  the  rate  of  combustion  and  other  conditions, 
such  as  the  presence  or  absence  of  diluting  substances  (e.g.,  nitro- 
gen), and  the  initial  temperature.  The  calorific  power  of  fuels  is 
sometimes  measured  by  the  weight  of  water  at  a  given  temperature 
evaporated  by  a  unit  weight  of  the  fuel;  this  is  called  the  evapora- 
tive power. 

Regeneration  is  a  method  for  preheating  air  or  fuel  gas  to 
obtain  a  higher  temperature  of  combustion,  or  greater  economy 
in  fuel.  To  effect  this  there  are  provided  two  or  more  set  of  flues 
(regenerators ;  regenerative  chambers)  which  are  filled  with 
checker  work  (checkers),  i.e.,  fire-bricks  laid  in  such  a  way  that 
small  passages  are  left.  The  products  of  combustion  are  passed 
through  one  set  for  a  certain  period,  their  heat  being  absorbed  in 
great  part  by  the  checker  work,  after  which  the  air  (or  air  and  gas 
separately)  are  passed  through  in  the  opposite  direction,  before 
entering  the  furnace,  the  products  of  combustion  then  heating 
another  set.  In  heating  blast  in  a  stove,  or  removing  the  heat 
from  blast  furnace  gas  in  a  washer,  for  example,  application  is 


204  HEAT 

usually  made  of  the  counter-current  principle.     This  is  to  bring 

.the  two  substances  together  so  there  is  always  as  much  difference 

-    in  temperature  as  possible  between  them  so  that  there  will  be  the 

greatest  total  transfer  of  heat.     For  example  with  the  blast  stove, 

the  hearth  or  chamber  where  the  gases  burn  is  the  hottest  part 

and  the  coolest  part  is  at  the  stack;  the  cold  blast  should  enter 

near  the  stack  and  leave  through  the  hearth. 

Recuperation  is  also  a  system  for  preheating  gases  (usually  only 
the  air):  the  products  of  combustion  are  caused  to  pass  around 
and  heat  iron  pipes  through  which  the  air  for  combustion  is  con- 
veyed to  the  furnace. 

The  mechanical  equivalent  of  heat  is  the  value  for  converting 
.    heat  units  into  mechanical  units  (or  vice  versa} : 
iB.T.U.  =  778  foot-pounds, 
i  kg.  cal.  =  426.9  kilogrammeters. 

Except  in  certain  cases  when  undergoing  critical  changes,  such 
as  the  melting  of  ice  (or  the  reverse,  when  water  freezes),  bodies 
expand  when  heated  and  contract  when  cooled  (i.e.,  when  heat  is 
removed).  The  degree  of  expansion  (or  contraction)  usually 
varies  at  different  temperatures  and  in  different  substances,  and 
is  generally  expressed  as  a  proportion  of  the  length  at  a  standard 
temperature  (commonly  o°  C.  or  32°  F).  This  is  termed  the 
coefficient  or  factor  of  expansion  and  the  range  of  temperature 
for  which  it  is  correct  (or  approximately  true)  should  be  stated. 

If  a  substance  is  altered  by  heat  it  is  said  to  be  thermolabile  ; 
particularly  where  decomposition  results  it  is  pyrolytic  (pyrolysis)  ; 
if  unchanged  thermostable  or  (particularly  in  the  sense  of  being 
non-conductive)  refractory.  A  body,  such  as  a  Welsbach  man- 
tle, which  glows  when  heated  is  said  to  be  pyrognomic ;  one 
which  burns  spontaneously,  upon  contact  with  air  or  moisture, 
pyrophoric. 

Temperature  Measurement. — The  temperature  of  a  body  is  the 
degree  of  sensibile  heat  which  it  possesses,  and  is  an  indication 
of  its  ability  to  impart  heat  to  or  receive  heat  from  an  adjacent 
body  which  is  respectively  at  a  lower  or  a  higher  temperature. 
It  is  stated  in  degrees  of  a  scale  (thermometric  or  pyrometric 
scale)  based  on  certain  fixed  points,  such  as  melting  points 
or  boiling  points,  of  various  substances  taken  as  standards  of 
reference.  There  are  two  scales  in  common  use,  the  Fahrenheit 
(English)  scale  (F),  and  the  Centigrade  (Celsius  or  metric) 
scale  (C),  and  a  third,  the  Reaumur  scale  (R),  which  is  occasion- 
ally encountered;  these  compare  with  each  other  as  follows: 

C  F  R 

B.  P.  Water 100  212  80 

M.  P.  ice o  32  o 

Difference 100  180  80 

Ratio 5  9  4 

For  conversion  from  one  to  another: 
C  =  %(F  -  32)  =  MR- 
F  =  %C   +  32    =  %R  +  32. 
-  32)  =  %C. 


205 


°C        °F           °C         °F         °C       °F          °C       °F         °C       °F 

300-i 

=^572             600n 

^1112           900-1 

-1652          1200-n 

^2192         ISOO-i 

pr2732 

• 

—  60 

"  nnn 

—  40 

OQ 

-20 

90  - 

—  50                  90~ 

-90                  °°~ 

-  30 

—  70 

-10 

80  — 

~  40                 80- 

~80                  80- 

-  20                  80J 

E-  60               80- 

-2700 

-  30 

-  70 

-  10 

-  50 

-90 

70  - 

-  20                   70- 

-60                 70- 

-1600              70- 

-  40                70- 

-80 

-  10 

-  50 

-  90 

-  30 

-70 

00  - 

—  500               60- 

-  40                  60  - 

^80                 60- 

-20                60  - 

-60 

- 

-  90 

-30 

-  70 

-  10 

-50 

50  - 

-80                 50  - 

-  20                  50- 

--  60                  50- 

^2100            50- 

-40 

40  - 

—  70 

r  60             4°- 

~  10                dn  ' 

-1000 

^40                   4°  - 

—80                 40  ~ 

-30 
-20 

30  ~~ 

—  50 

-  3°                  30- 

—  70               o« 

-10 

—  40                      T 

-  80 

-  20 

—  60 

-2600 

20  - 

~  3o                 20- 

-  70                20  - 

-10                  20  — 

-50               20  - 

-90 

-  20 

-  60 

-1500 

-40 

-80 

10  - 

-10                 10  - 

150                  10- 

-90                 10- 

^-30                10- 

-70 

- 

—400 

—  40 

-  80 

—  20 

r&0 

200- 

500- 

-  30              800  — 

L  70             UOO- 

—  10           1400— 

-50 

90  - 

ITO             «>- 

:fj       90- 

90- 

^y*    90- 

-40 
-30 

80  — 

r60         '  80- 

r900             80- 

80- 

80- 

-20 

-  50 

-90 

-  30 

-  70 

-10 

70  - 

-40                  7Q_ 

-  80                  70  - 

-  20                  70  - 

-60                70_ 

-2500 

-  30 

-  70 

-  10 

-  50 

-90 

60  - 

-20                  60  - 

-  60                  60  - 

-1400              60  - 

-40                60  - 

-80 

- 

-  10 

-  50 

-  90 

-  30 

^70 

50  - 

—300               50- 

-40                  50- 

-80                  50- 

—  20                50  — 

* 

-  90 

-  30 

-70                        ' 

-  10 

-50 

40  - 

-  80 

:-  20 

-  60 

-1900          40~ 

-40 

30  — 

—  70 

-  10                  30- 

-50                  30  _ 

-90                                 y. 

-30 

—  60 

-800 

-  40 

r  80 

-20 

20  - 

-50                  20- 

-90                 20- 

-30                  20- 

-70                20- 

-10 

-40 

-  80 

-  20 

^2400 

10  - 

-30                   10- 

-  70                 10  - 

1  10                 10  - 

-50                10  - 

-90 

- 

—  20 

-  60 

1300 

—  40 

—  80 

100- 

rlO             400- 

-  50              700- 

_  90            1000— 

=  30           1300- 

-70 

90  - 

^             *>- 

-  40 

-  30                 90  - 

^70                  90~ 

^10           °°- 

-60 

r50 

80  - 

80- 

120                 80- 

-60                  go  - 

-1800           80J 

L40 

-70 

-10 

-50 

r90             M  . 

-30 

70  - 

70- 

-700              70- 

-40                  70- 

~  e°                70  - 

-20 

- 

—  50 

-  90 

-  30 

-70 

-10 

60  - 

-40                  60  - 

-80                  60- 

-20                 60  - 

-60                60- 

-2300 

-  30 

-  70 

-  10 

-  50 

-90 

50- 

^20                  50  - 

-  60                  50- 

-1200              50  - 

-40                50- 

-80 

- 

-10 

—  50 

-90                      ~ 

—  30 

-70 

40  - 

-loo          4°- 

-  40                   40  ~~ 

-  80 

—  20                40  "~ 

-GO 

30  - 

-»o                J 

-80 

:S       - 

:67o°            "-_ 

~-    10                30- 
-1700 

-50 
L40 

20  - 

20- 

7™                 20  - 

-50                  20  - 

-90                20- 

-30 

—  60 

-600 

-  40 

-  80 

-20 

10  _ 

-50                  10  - 

^90                 10- 

-30                 10- 

-70                10- 

-10 

- 

-40 

-  20 

1.60 

-2200 

0  — 

—  32          .    300- 

ir-1652       1200-J 

&2192 

C             °F     °C              "F     °C           ~~°F     °C              °F°C                'F 

PIG.  24. — Conversion  scale  for  Centigrade  and  Fahrenheit  tem- 
peratures.    (Tiemann,  T.  A.  I.  M.  E.,  1915.) 


206  HEAT 

De  Lisle  's  scale  assigns  150  degrees  to  the  range  from  the 
melting  point  of  ice  to  the  boiling  point  of  water.  The  abso- 
lute scale  is  based  on  absolute  zero  which  is  generally  defined 
as  the  temperature  at  which  all  molecular  motion  ceases.  It 
corresponds  ^  to  —  ^273°  C.  or  —  459-4°  F.,  and  was  arrived  at 
from  a  consideration  of  the  effect  of  temperature  on  the  volume 
of  a  perfect  gas;  in  calculations,  particularly  those  relating  to 
gases,  these  values  are  added  to  ordinary  temperatures,  giving 
absolute  temperatures.  In  honor  of  Lord  Kelvin  it  has  been 
proposed  to  designate  absolute  temperatures  in  centigrade  units 
as  degrees  K.  A  normal  scale  is  one  based  on  rigorously  defined 
points  and  prescribed  methods  of  determination.  Particularly 
in  connection  with  the  heating  and  cooling  of  bodies  it  has  been 
suggested  that  the  letters  C  and R  be  prefixed  to  indicate  whether 
the  temperature  was  falling  or  rising  respectively,  thus 

C  750°  C.:  falling  temperature. 
R  827°  C.:  rising  temperature. 

The  measurement  of  temperatures  is  termed  thermometry  or 
pyrometry.  The  instruments  by  which  temperatures  are  deter- 
mined are  usually  roughly  distinguished  as  thermometers  for 
ordinary  or  moderate  temperatures,  and  pyrometers  for  high 
temperatures,  although  these  names  may  be  used  more  or  less 
interchangeably.  An  instrument  for  measuring  temperatures  by 
radiation  is  termed  a  radiometer  (microradiometer  or  radio  - 
micrometer) ;  particularly  for  losses  due  to  radiation,  a  thermo- 
radiometer.  A  thermoscope  is  an  instrument  for  showing 
differences  or  changes  in  temperature  without,  necessarily,  great 
accuracy;  a  differential  thermoscope,  one  for  indicating  the  rela- 
tive condition  of  two  bodies.  A  recording  thermometer  is 
sometimes  termed  a  thermograph  or  thermometrograph. 

Thermomete'rs  depend  upon  the  nearly  uniform  expansion  or 
contraction  when  various  substances  are  heated  or  cooled,  some- 
times referred  to  as  a  mechanical  thermometer  or  expansion 
pyrometer.  The  kind  most  commonly  met  with  is  a  suitably 
graduated  glass  tube  containing  mercury  (mercury  or  mercurial 
thermometer) ;  by  employing  a  gas,  such  as  nitrogen,  the  pressure 
of  which  prevents  boiling  at  the  normal  temperature  of  about 
356°  C.  (673°  F.),  it  may  be  used  for  temperatures  up  to  about 
550°  C.  (1020°  F.)  for  high-range  mercury  thermometers  (Bur- 
gess, 362).  Other  forms  for  special  purposes  may  employ  ethyl 
alcohol  or  ether  (spirit  thermometer),  or  air  or  other  gas  (air ther- 
mometer, gas  thermometer) .  Gas  thermometers  may  be  either 
constant  volume  (variable  pressure)  thermometers,  where  the 
volume  and  mass  are  maintained  constant,  or  constant  pressure 
(variable  volume)  thermometers,  where  the  mass  of  gas  varies 
but  its  pressure  and  volume  remain  the  same.  A  normal  ther- 
mometer is  one  based  on  a  normal  scale  (see  above) .  A  metallic 
(bimetallic  or  differential)  thermometer  depends  on  the  different 
degrees  of  expansion  and  contraction  of  two  pieces  of  different 
metals  connected  together.  A  chromatic  thermometer  is  based 


HEAT  207 

on  the  different  colors,  due  to  internal  strains,  when  polarized  light 
is  passed  through  a  piece  of  glass,  one  edge  of  which  rests  on  a 
heated  body. 

The  following  classification  of  pyrometers  is  largely  taken  from 
Burgess'  "Measurement  of  High  Temperatures:" 

1.  Gas  pyrometer  (Pouillet,  Becquerel's  volumetric  or  volu- 
menometric  thermometer,  Sainte-Claire-Deville,  Barus,  Chap- 
puis,  Holborn,  Callendar,  Day):  "Utilizes  the  measurement  of 
change  in  pressure  of  a  gaseous  mass  kept  at  constant  volume. 
Its  great  volume  and  its  fragility  render  it  unsuitable  for  ordi- 
nary measurements;  it  serves  only  to  give  the  definition  of  tem- 
perature and  should  only  be  used  to  standardize  other  pyro- 
meters  (pp.    9-10).     Industrial    types  have  been    devised    by 
Bristol  and  Wiborgh. 

2.  Calorimetric  pyrometer,   specific  heat  pyrometer,  water 
pyrometer,  hydropyrometer   (Regnault,  Violle,  Le    Chatelier, 
Siemens):  "Utilizes  the  total  heat  of  metals,  platinum  in  the 
laboratory  and  nickel  in  industrial  works.     It  is  to  be  recom- 
mended for  intermittent  researches  in  industrial  establishments 
because  its  employment  demands  almost  no  apprenticeship  and 
because  the  cost  of  installation  is  not  great"  (p.  10). 

3.  Radiation  pyrometer  (Rosetti,  Langley's  bolometer,  Boys, 
Callendar   disk   radio-balance,   Joly's   meldometer,    Crooke's 
radiometer,  Pouillet's  pyrheliometer,  Fery's  pyrometer,  mirror 
telescope,  and  spiral  pyrometer,  Thwing,  Brown,  thermo-electric 
telescope,  Violle's  actinometer,  Gasparin's  pyrometer,  Foster) : 
"Utilizes  the  total  heat  radiated  by  warm  bodies.     Its  indica- 
tions are  influenced  by  the  variable  emissive  power  of  the  differ- 
ent substances.     It  is  convenient  for  the  evaluation  of  very  high 
temperatures  which  no  thermometric  substance  can  withstand 
(electric  arc,  sun,  very  hot  furnaces)  or  when  it  is  not  convenient 
to  approach  the  body  whose  temperature  is  wanted.     It  can  be 
made   self-registering"    (p.    10).     Stefan's  law    (Stefan-Boltz- 
mann's  law)  is  that  the  total  energy  radiated  by  a  black  body  is 
proportional  to  the  fourth  power  of  its  absolute  temperature. 
The  conception  of  a  black  body  or  absolutely  black  body  is  due 
to  Kirchhoff  which  he  defined  as  one  which  would  absorb  all  radia- 
tions falling  on  it,  and  would  neither  reflect  nor  transmit  any; 
a  black  body  is  also  called  an  integral  radiator  or  full  radiator. 
Unless  substances  are  in  the  condition  of  a  black  body  their 
emissive  power  (for  light)  will  not  necessarily  be  the  same  for  the 
same  temperature.     A  black  body  temperature  or  black  tem- 
perature is  understood  to  mean  that  shown  by  a  radiation  pyro- 
meter calibrated  against  a  black  body.     Gray  body  is  the  name 
which  has  been  applied  to  a  body  not  black  but  whose  properties 
of  radiation  have  a  direct  and  constant  proportion  to  that  of  a 
black  body.     Radiation  pyrometers  may  also  be  based  on  the 
electric  current  set  up  in  a  circuit  of  two  dissimilar  metals  when 
their  junction  is  heated;  this  is  called  a  thermopile,  which  has 
been  employed  by  Nobili  and  Melloni.     . 

4.  Optical   pyrometer    (Becquerel,   Le    Chatelier,   Wanner, 
Holborn-Kurlbaum,  Morse  thermogage,  Fery  absorption  pyro- 


208  HEAT 

meter  and  spectral  pyrometer,  Henning's  spectral  pyrometer, 
Shore  pyroscope,  Mesure  and  Noiiel  pyroscope,  Crova,  stellar 
pyrometer,  modifications  of  a  photometer,  flicker  photometer, 
Nordman's  heterochrome  photometer,  pyrophotometer) :  "  Util- 
izes either  the  photometric  measurement  of  radiation  of  a  given 
wave  length  of  a  definite  portion  of  the  visible  spectrum,  or  the 
disappearance  of  a  bright  filament  against  an  incandescent  back- 
ground. Its  indications,  as  in  the  preceding  case  but  to  a  much 
less  degree,  are  influenced  by  variations  in  emissive  power. 
The  intervention  of  the  eye  aids  greatly  the  observations,  but 
diminishes  notably  their  precision.  This  method  is  mainly  em- 
ployed in  industrial  works  for  the  determination  of  the  tempera- 
tures of  bodies  difficult  of  access.  For  example,  of  bodies  in 
movement  (the  casting  of  a  metal,  the  hot  metal  passing  to  the 
rolling  mill).  It  can  be  used  to  establish  the  highest  tempera- 
tures, and  is  the  best  method  for  use  above  1700°  C.  (3090°  F.) 
in  the  laboratory  and  the  works"  (p.  10).  Draper's  law  is  that 
all  bodies  acquire  incipient  luminosity  at  the  same  temperature. 
Selenium  has  been  employed  to  measure  the  temperatures  of 
incandescent  bodies  due  to  the  fact  that  its  electrical  resistance 
is  affected  by  light. 

5.  Electrical  Resistance  pyrometer  (Siemens,  Callendar  and 
Griffith,  Waidner  and  Burgess) :     "  Utilizes  the  variations  of  the 
electrical  resistance  of  metals  (platinum)  with  the  temperature. 
This  method  permits  of  very  precise  measurement  to  1000°  C. 
(1830°  F.),  but  requires  the  employment  of  fragile  apparatus. 
It  merits  the  preference  for  very  precise  investigations  in  labora- 
tories.    As  a  secondary  instrument  for  the  reproduction  of  a 
uniform  temperature  scale  throughout  the  range  in  which  the 
platinum  resistance  pyrometer  can  be  used,  to  1000°  C.  except  in 
very  heavy  wire,  it  is  unsurpassed  in  precision  and  sensibility. 
It  is  also  now  constructed  in  convenient  form  for  industrial  use" 
(pp.  10-11).     A  logometer  is  an  instrument  designed  for  the 
measurement  of  the  ratio  of  two  electric  currents  (Burgess,  221); 
Northrup's  ratiometer  is  somewhat  similar.    Holborn  and  Wien 
used  palladium  instead  of  platinum. 

6.  Thermo-electric  pyrometer  (Becquerel,  Barus,  Le  Chate- 
lier) :     "Utilizes  the  measurement  of  electromotive  forces  devel- 
oped by  the  difference  in  temperature  of  two  similar  electromo- 
tive junctions  opposed  to  one  another.     In  employing  for  this 
instrument   a  Deprez-d' Arson val  galvanometer  (galvanometric 
method)  with  movable  coil,  one  has  an  apparatus  easy  to  handle 
and  of  a  precision  amply  sufficient  for  industrial  and  many 
scientific  uses.     With  a  potentiometer  (potentiometer  method), 
an  instrument  is  obtained  of  the  most  considerable  precision, 
available  for  use  to  1600°  C.  (2910°  F.),  or  even  to  1750°  C.  (3180° 
F.)  with  proper  precautions.     This  pyrometer  was   used   for  a 
good  many  years  in  scientific  laboratories,  before  it  spread  into 
general  use,  where  it  also  renders  most  valuable  service"  (p.  u). 
The  two  dissimilar  elements  are  termed  a  couple,  thermo-couple, 
thermo-element,  or  thermoelectric  pair.    For  high  temperatures 
and  special  work  they  commonly  consist  of  combinations  of 


HEAT  209 

platinum  and  platinum  with  about  10%  of  rhodium  (Le  Chate- 
lier's  couple),  platinum-palladium,  etc.  (Becquerel),  etc.;  these 
are  termed  noble  or  rare  metal  couples  owing  to  their  compara- 
tive freedom  from  oxidation.  Base  metal  couples  are  those 
which,  for  the  sake  of  cheapness,  are  made  of  combinations  of  the 
more  ordinary  metals  or  alloys,  such  as  copper,  nickel,  iron,  etc.; 
these  are  usually  restricted  to  the  lower  temperatures,  say  not 
over  about  900  or  1000°  C.  (1650  or  1830°  F.)  on  account  of  their 
greater  fusibility  or  oxidizability.  Two  special  alloys  for  this 
purpose  are  constantan  (konstantan,  advance  alloy)  with  copper 
50  and  nickel  50,  or  copper  60  and  nickel  40;  and  manganin 
with  approximately  copper  84,  nickel  4,  and  manganese  12. 
Compound  couples  are  those  which  either  consist  of  two  or  more 
couples  in  series,  to  give  greater  sensibility,  or  where  (to  save  ex- 
pense) cheaper  substances  are  used  for  the  portion  not  subjected  to 
the  maximum  temperature.  The  couple  is  formed  by  joining  the 
two  wires  at  one  end  by  twisting  or  preferably  welding  together, 
called  the  hot  junction  (H.  J.).  At  their  other  ends  they  are  con- 
nected to  copper  wires  or  suitable  lead  wires  which  are  connected 
with  the  galvanometer  or  other  measuring  device;  these  other 
ends,  or  cold  junction  (C.  J.) ,  of  the  couple  are  properly  maintained 
at  a  constant  temperature  usually  by  inserting  in  melting  ice  or 
other  substance  whose  temperature  is  known  as  the  determina- 
tion indicates  the  difference  in  temperature  between  the  two 
junctions.  Complete  expression,  however,  from  the  total  e.m.f. 
developed  in  the  thermoelectric  circuit  requires  account  to  be 
taken  of  (i)  the  Thomson  effect :  the  electromotive  forces  gener- 
ated due  to  differences  in  temperature  along  a  homogeneous  wire; 
(2)  the  Peltier  effect:  due  to  the  heating  of  the  junction  of  two 
dissimilar  metals  anywhere  in  the  circuit;  (3)  the  Becquerel 
effect :  the  electromotive  forces  developed  by  physical  or  chem- 
ical inhomogeneity  in'a  single  wire  (Burgess) .  The  electromotive 
force  generated  is  ascertained  either  by  the  opposition  (potenti- 
ometer) method  or  by  the  galvanometric  method,  the  former 
being  the  more  accurate. 

7.  Contraction  pyrometer   (Wedgewood's  contraction  pyro- 
scope) :     "  Utilizes  the  permanent  contraction  that  clayey  mate- 
rials take  up  even  when  submitted  to  temperatures  more  or  less 
high.     It  is  employed  today  only  in  a  few  pottery  works" 
(p.  n). 

8.  Fusible  cones  (Seger,  Orton):  "Utilizes  the  unequal  fusi- 
bility of  earthenware  blocks  of  varied  composition.     They  give 
only  discontinuous  indications.     Such  blocks  studied  by  Seger 
are  spaced  so  as  to  have  fusing  points  distant  about  20°  C. 
They  are  in  general  use  in  pottery  works  and  in  some  similar 
industries  (p.  n).     This  method  may  be  classed'as  fusing  point 
or  melting  point  pyrometry.     In  addition  to  the  earthenware 
cones,  similar  forms  may  be  made  of  a  series  of  salts  (Grenet), 
or  of  metals  and  alloys  (Prinsep) ;  these  are  sometimes  referred 
to  as  sentinels  or  sentinel  pyrometers. 

9.  Pyrometers  based  on  flow  or  on  pressure  of  air  or  vapor 
(Hobson,  Uhling-Steinbart,  Job,  Fournier). 

U 


2IO 


HEAT— HEAT  OF  COMBUSTION 


10.  Recording   pyrometers:  (Roberts-Austin,   Callendar,  Le 
Chatelier,  Siemens  and  Halske).     Those  which  are  provided  for 
plotting,  either  continuously  or  at  intervals,  a  chart  showing 
times  with  corresponding  temperatures  (p.  12). 

11.  Temperature  colors  are  those  shown  to  the  eye  by  incan- 
descent bodies  at  different  temperatures.     The  color  identities 
for  different  temperatures  have  been  investigated  by  Pouillet  and 
are  shown  below  in  what  is  known  as  Pouillet's  color  scale : 


Color  names 


Degrees  C. 


Degrees  F. 


Visible  color,  first  visible  red,  black  red.  .  . 
Dull  red,  low  red  

525 
700 

970 
1290 

Red,  incipient  cherry,  blood  red  
Cherry,  cherry  red,  bright  red  
Bright  cherry  . 

800 
900 

IOOO 

1470 
1650 
1830 

Dull  orange  
Bright  orange  
White  

IIOO 
1200 
I30O 

2010 
2190 
2370 

Bright  white  
Dazzling  white  

1400 
I5OO 

2550 
2730 

Black  heat  is  any  temperature  below  visible  color. 
12.  Miscellaneous  Methods:  Carnelly  and  Burton's  dilution 
pyrometer  is  based  on  the  increase  in  the  temperature  of  a  constant 
stream  of  water  led  through  a  furnace  or  other  heated  chamber. 
An  air  dilution  pyrometer  is  usually  arranged  so  an  amount  of 
cold  air  at  known  temperature  is  mixed  with  a  known  volume  of 
heated  blast,  etc.,  and  the  temperature  of  the  latter  determined 
from  the  temperature  of  the  mixture.  Uhling  and  Steinbart's 
transpiration  pyrometer  or  hot  blast  pyrometer  is  based  on  the 
varying  rate  at  which  a  gas  will  flow  through  a  small  orifice  when 
heated  to  different  temperatures.  Threw's  pyrometer  is  some- 
what similar  in  principle.  Schaffer  and  Budenberg's  thalpotassi- 
meter  or  vapor  pressure  pyrometer  employs  the  pressure  of  the 
saturated  vapor  of  certain  liquids  (i.e.,  when  both  liquid  and 
vapor  are  present  together).  Wiborgh's  thermophone  is  a 
contrivance  consisting  of  a  small  quantity  of  an  explosive 
enclosed  in  a  refractory  material  which  is  thrown  into  a  furnace, 
the  temperature  being  calculated  from  the  length  of  time  before 
the  explosion  occurs.  An  acoustic  signal  is  an  arrangement 
consisting  of  a  wire  connected  with  an  electric  clock;  when  the 
wire  is  melted  an  alarm  is  given.  A  spike  indicator,  used  to 
determine  the  temperature  of  a  fused  salt  bath,  is  an  iron  rod 
which  is  dipped  in  the  bath,  and  the  temperature  calculated 
from  the  amount  congealed  and  the  corresponding  time  required 
to  dissolve  it  off,  conditions  being  maintained  uniform  (Brearly). 
Sauveur  and  Whiting's  thermomagnetic  selector  was  a  device 
to  determine  those  rails  (or  similar  objects  which  were  finished 
at  a  temperature  below  the  critical,  so  that  their  magnetic 
properties  were  restored;  it  was  arranged  to  stamp  such  rails. 

Heat  Balance. — Of  a  blast  furnace:  see  page  36. 

Heat  of  Combustion. — See  pages  201  and  203. 


HEAT  CRACK— HEAT  TREATMENT      2 1 1 

Heat  Crack.— See  Crack. 

Heat  of  Disgregation. — See  page  202. 

Heat  Energy. — See  page  199. 

Heat  of  Expansion. — See  page  202. 

Heat  of  Formation. — See  page  200. 

Heat  of  Fusion. — See  page2oi. 

Heat  Interception,  Zone  of. — In  a  blast  furnace:  see  page  36. 

Heat  of  lonization. — See  page  201. 

Heat  Measurement. — See  page  201. 

Heat  of  Neutralization. — See  page  201. 

Heat  Refining.— See  page  213. 

Heat  Relief  .—See  page  288. 

Heat  of  Solution. — See  page  201. 

Heat,  Spontaneous  Evolution  of. — See  page  199. 

Heat  Sums. — Law  of:  see  page  201. 

Heat  Test. — A  test,  either  chemical  or  physical,  representing  a  heat 
or  melt  of  steel.  This  term  was  formerly  applied  to  a  tensile 
test  made  op  a  round  (about  %"  in  diameter)  forged  down  from 
a  ladle  test  ingot  or  rolled  from  a  billet;  same  as  billet  test. 

Heat  Tinting.— See  page  288. 

Heat  Treatment  (Thermal  Treatment). — Heat  treatment  in  its 
most  general  sense  may  be  taken  to  mean  the  application  of  heat 
either  to  make  the  metal  easier  to  work  by  rendering  it  softer  or 
more  ductile,  or  to  secure  certain  desired  (and  beneficial)  changes 
in  its  constitution  and  physical  properties  without  mechanical 
work .  By  common  usage,  however,  the  term  has  become  restricted 
to  the  latter  application,  for  which  the  writer  has  suggested  the 
following  definition: 

Heat  treatment  is  the  change,  or  the  series  of  changes,  in  tempera- 
ture, and  also  the  rate  of  change  from  one  temperature  to  another, 
brought  about  to  secure  certain  desired  conditions  or  properties  in  a 
metal  or  alloy. 

The  term  "heat  treatment"  is  frequently  but  incorrectly  used 
in  the  restricted  sense  of  quenching  followed  by  reheating,  as 
applied  to  axles,  etc.;  when  so  used  it  is  not  considered  to  apply 
to  annealing  or  any  other  treatment  properly  covered  by  this 
term. 

In  connection  with  what  follows  the  article  on  Metallography 
should  be  consulted  for  explanations  of  certain  special  terms 
necessarily  used.  For  processes  or  terms  employed  chiefly  for 
one  class  of  product  reference  should  be  made  to  special  articles, 
such  as  Malleable  Castings,  Sheets  and  Tin  Plate,  Special  Steels, 
and  Wire. 

Heat  treatment,  like  a  good  rule,  will  work  both  ways,  and 
consequently  if  it  is  not  employed  intelligently,  or  if  its  presence 
and  effect  are  overlooked,  when  material  is  heated  simply  for  the 
purpose  of  working,  the  results  may  be  disappointing  or  even 
disastrous.  It  should  be  appreciated  that  heat  treatment  acts 
as  an  intensifier  in  the  development  of  the  properties  of  the  steel, 
much  as  in  the  treatment  of  the  photographic  plate:  if  the  initial 
quality  is  good  it  will  be  greatly  improved,  but  if  bad  the  final 
state  of  that  steel  is  likely  to  be  worse  than  the  first,  although 


212  HEAT  TREATMENT 

in  some  cases,  if  this  is  known,  special  corrective  steps  can  be 
taken  which  may  effect  a  partial  but  rarely  a  complete  cure. 
Whether  it  will  prove  beneficial  or  harmful  will  also  depend  upon 
the  degree,  the  rate,  and  above  all  the  uniformity  of  heating  and 
cooling.  Too  much  emphasis  cannot  be  laid  upon  this  question 
of  uniformity;  it  means  the  same  kind  of  material  treated  in  the 
same  way  to  get  the  same  results;  these  three  cardinal  points  may 
be  tabulated  as  follows: 

1.  Uniformity  of  material: 

(a)  The  same  grade — composition  within  prescribed  limits. 

(&)  Homogeneity  of  material — freedom  from  chemical 
defects  represented  by  harmful  segregation,  inclusion  of 
foreign  substances,  etc.,  freedom  from  physical  defects, 
such  as  piping,  cavities,  injurious  and  severe  strains 
which,  as  an  extreme  case,  have  actually  developed  cracks. 

2.  Uniformity  of  treatment: 

(a)  Suitable    equipment,    including    furnaces,    quenching 
baths,  and  pyrometers;  the  capacity  should  be  ample  so  it 
will  not  be  overtaxed  in  handling  a  given  output. 
(6)  The  heating  and  cooling  must  be  adjusted  so  that  each 
piece  from  end  to  end  throughout  the  section  from  outside  to 
center,  as  well  as  all  the  pieces  in  a  lot  treated  together  shall,  as 
nearly  as  possible  be  at  the  same  temperature  at  all  times. 

3.  Uniformity  of  results :  If  the  other  two  conditions  have  been 
met  this  one  is  found  to  follow.     Means  should,  however,  be 
provided  for  constantly  checking  results  in  order  that  any  errors 
or  carelessness  will  be  promptly  discovered  and  corrected.     A 
further  discussion  of  these  conditions  will  be  found  in  connection 
with  the  effect  of  mass. 

Heat  treatment  affects  the  physical  or  mechanical  properties  in 
two  ways,  by  regulating  (a)  the  constituents,  and'(6)  the  grain 
size.  The  effect  which  a  given  heat  treatment  will  produce  varies 
considerably  with  the  chemical  composition;  carbon  is  the  prin- 
cipal or  dominant  element,  and  certain  other  elements,  such  as 
manganese,  chrome,  tungsten,  etc.,  are  also  very  noticeable  in  this 
respect.  The  effect  of  the  special  elements  is  considered  more 
particularly  under  Special  Steel. 

Special  heat  treatment  may  be  classified  under  the  four  heads; 
(i)  hardening,  (2)  tempering,  (3)  annealing,  and  (4)  grain  refin- 
ing. Before  discussing  in  detail  the  first  three  of  these  operations, 
the  effect  of  carbon  and  grain  refining  will  be  considered. 

Effect  of  Carbon. — It  has  already  been  stated  that  carbon  is  the 
'element  which,  more  than  any  other  constituent  of  steel,  governs 
or  controls  its  properties.  This  effect  is  due  to: 

1.  The  condition  of  the  carbon. 

2.  The  distribution  of  the  carbon. 

As  regards  its  condition,  the  carbon  may  exist  (a)  in  the  free 
state,  as  graphite,  which  in  steels  is  of  interest  only  as  a  possible 
impurity;  (6)  in  chemical  combination  with  iron,  Fe3C  or 
cementite;  and  (c)  in  solid  solution  in  gamma  (or  beta)  iron  in 
which  it  is  dissolved  (absorbed)  either  in  its  elemental  form  or 
more  probably  as  the  carbide. 


HEAT  TREATMENT  2 1 3 

The  distribution  of  carbon  may  be  either  homogeneous  or 
heterogeneous.  It  is  homogeneous  only  when  the  carbon  is  in 
perfect  solid  solution  as  in  such  case  it  must  be  completely 
diffused  (rarely,  equalized  or  absorbed)  throughout  the  if  on  in  the 
same  way  that  salt  is  diffused  when  dissolved  in  water,  so  that 
individual  particles  of  it  cannot  be  detected  even  by  the  aid  of 
the  most  powerful  microscope;  unfortunately,  however,  a 
solution,  particularly  a  solid  solution,  may  be  more  highly 
concentrated  in  one  portion  than  in  another,  due  to  incomplete 
diffusion  or  imperfect  mixing,  and  hence  is  to  this  extent  hetero- 
geneous. This  solid  solution  is  ordinarily  normal  at  high  temper- 
atures above  the  upper  critical  point  AS  (see  Metallography), 
and  if  it  can  be  preserved  when  cold  by  sufficiently  rapid  cool- 
ing, its  homogeneity  must  also  be  preserved. 

The  chief  (and  unavoidable)  cause  for  heterogeneity  is  the 
form  known  as  cementite,  either  free  or  as  the  eutectoid  mixture 
with  pure  iron  or  ferrite  known  as  pearlite;  it  may  also  be 
present  with  other  constituents.  This  condition  is  reached 
either  by  slow  cooling  from  above  the  upper  critical  point  or  by 
reheating  to  temperatures  inferior  to  A.CI;  the  restraint  of  the 
atoms  is  sufficiently  removed  to  permit  the  transformation  of 
some  or  all  of  the  iron  into  the  alpha  variety.  The  carbon 
originally  in  solution  in  this  portion  is  thereby  automatically 
expelled  or  precipitated  as  cementite.  There  will  therefore 
result  a  mixture  of  cementite  and  ferrite  resembling  pearlite 
with  an  excess  of  one  of  these  substances  unless  of  eutectoid 
composition  (about  0.85  %  carbon) ;  as  it  has  been  claimed  that 
true  pearlite  is  only  produced  by  slow  cooling,  it  is  suggested  that 
the  mixture  resulting  from  reheating  be  termed  pearlpid  (of  the 
nature  of  pearlite),  and  in  this  discussion  the  distinction  will  be 
observed.  Unless  the  temperature  is  close  to  A c\  there  is  still  too 
much  viscosity  to  permit  the  molecules  sufficient  freedom  of 
movement  to  cause  any  marked  segregation  of  the  ferrite  and 
cementite,  so  the  pearloid  has  an  extremely  fine  structure. 
Where  the  temperature  and  time  of  cooling  are  sufficient,  the 
formation  of  relatively  coarse  pearloid  will  occur.  The  segrega- 
tion just  referred  to  is  intended  in  a  microscopical  sense,  and  is  not, 
as  commonly  understood  by  the  term,  what  is  detected  by  ordi- 
nary methods  of  chemical  analysis.  In  actual  practice  it  is  well 
known  that  of  two  pieces  of  the  same  steel,  one  merely  annealed 
while  the  other  is  quenched  and  then  reheated  to  Aci,  the  latter 
will  possess  much  better  physical  properties,  not  only  in  regard 
to  strength,  but  to  ductility  as  well.  The  cause  for  this  is  princi- 
pally found  in  the  distribution  of  the  carbon,  as  the  material  is 
microscopically  more  homogeneous,  although  other  factors,  such 
as  the  effect  of  grain  size,  etc.,  may  contribute. 

Grain  size  and  growth  is  affected  by  heating  and  by  thermal 
or  heat  refining ;  grain  growth  is  also  referred  to  as  crystal- 
line growth,  growth  of  crystals  or  crystallization  by  annealing. 
Metals  and  alloys  are  composed  of  a  number  of  crystals  or 


214 


HEAT  TREATMENT 


1400 


E 


N 


M 


grains.  The  irregularity  of  their  form  is  due  to  the  fact  that  the 
growth  of  each  is  interfered  with  by  that  of  the  others  surrounding 
it.  Therefore,  it  is  only  under  special  conditions  that  perfect  crys- 
tals are  attained.  The  size  of  these  grains  depends  upon  the 
maximum  temperature  above  Ac\  at  which  they  have  been  free 
to  develop,  subject  to  the  following  conditions: 

If  a  piece  of  steel  is  heated  to  a  temperature  corresponding 
to  the  point  G  in  Fig.  25  (due  to  Howe),  and  is  then  cooled,  it  will 
be  found  to  have  a  grain  size  0  L  proportional  to  this  temperature. 
If  it  is  then  reheated  the  grain  size  will  remain  the  same  until 
Ac\  has  been  reached.  Immediately  on  passing  this  (as  at  N), 
the  grain  is  refined  to  the  minimum,  that  is,  from  ^V  to  /,  produc- 
ing a  refined  structure.  This  is  known 
as  the  refining  temperature  or  refining 
heat.  If  the  temperature  is  still  further 
raised  the  grain  size  increases  progres- 
sively as  shown  by  the  curve  J  D  G, 
and  this  cycle  of  changes  can  be  re- 
peated indefinitely,  provided  the  steel  is 
allowed  to  cool  uninterruptedly  from  the 
maximum  temperature  above  Ac\.  Ex- 
cept with  eutectoid  steel  which  has  a 
single  critical  point,  when  the  cooling 
reaches  the  upper  critical  point  a  sepa- 
ration of  the  excess  constituent  com- 
mences, and  continues  until  the  lower 
critical  point  is  reached,  to  form  an 
envelope  or  skeleton  structure  about 
what  then  becomes  the  eutectoid.  On 
reheating,  this  excess  substance  com- 
mences to  be  reabsorbed  or  dissolved 
when  the  lower  critical  point  is  passed, 
but  the  action  is  not  complete4  until  the 
upper  critical  point  has  been  reached.  Consequently  unless  this 
latter  temperature  is  exceeded,  portions  of  the  skeleton  will  remain 
and  prevent  a  real  grain  refinement.  As  a  matter  of  fact  hyper- 
eutectoid  steels  (with  carbon  over  0.85%)  do  not  possess  this 
difficulty  as  apparently  the  excess  cementite  crumbles  or  is 
broken  up  after  passing  the  lower  critical  point,  so  they  can  be 
treated  the  same  as  a  eutectoid  steel.  It  must  be  clearly  under- 
stood that  the  influence  of  time  on  grain  size  is  important. 
Unless  ample  time  is  given  at  the  maximum  temperature,  a 
given  grain  may  have  the  same  or  even  a  smaller  size  than  another 
held  longer  at  a  lower  temperature. 

MetcalP s  Experiment. — An  experiment  to  show  the  effect  of 
temperature  on  the  grain  size,  known  as  "Metcalf's  Experiment," 
illustrates  this  very  clearly.  A  description  of  this  experiment 
was  published  by  William  Metcalf  in  the  Metallurgical  Review 
(Vol.  I,  No.  3,  November,  1877),  and  because  of  its  value  as  well 
as  the  historical  interest  attaching  to  it,  the  following  extensive 
extract  is  given: 

To  show  this  effect  we  take  a  bar  of  steel  of  ordinary  size,  say 


O          P         L 

Grain-  Size 

FIG.  25. — Heat  refin- 
ing. (Howe,  "Iron,  Steel 
and  Other  Alloys.") 


HEAT  TREATMENT  2 1 5 

about  inch  by  half,  heat  6  or  8"  of  one  end  to  a  low 
red  heat,  and  nick  the  heated  part  all  around  the  bar  at  intervals 
of  half  to  three-quarters  of  an  inch,  until  eight  or  nine  notches  are 
cut.  This  nicking  is  done  at  a  red  heat  to  determine  the  fracture 
at  the  nicks.  Then  place  the  end  of  the  bar  in  a  very  hot  fire, 
leaving  the  balance  of  the  bar  so  much  out  of  the  fire  as  to  heat 
it  chiefly  by  conduction.  Heat  the  end  of  the  bar  in  the  fire  to 
white  heat,  or  until  it  scintillates,  and  allow  it  to  remain  until 
the  nick  furthest  from  the  end  in  the  fire  is  not  quite  red,  and  the 
next  barely  red.  Now,  if  the  pieces  be  numbered  from  one  to 
eight,  beginning  at  the  outer  end: 

No.  i  will  be  white  or  scintillating; 

No.  2  will  be  white; 

No.  3  will  be  high  yellow; 

No.  4  will  be  yellow  or  orange; 

No.  5  will  be  high  red; 

No.  6  will  be  red; 

No.  7  will  be  low  red; 

No.  8  will  be  black. 

As  soon  as  heated  as  above  described,  let  the  bar  be  quenched 
in  cold  water,  and  kept  in  the  water  until  quite  cold.  After 
cooling,  the  bar  should  be  carefully  wiped  dry,  especially  in  the 
notches.  An  examination  of  the  different  parts  by  the  file  will 
show  the  following,  if  high  (carbon)  steel  has  been  used: 

No.  i  will  scratch  glass; 

Nos.  2,  3,  4  will  be  excessively  hard; 

Nos.  5,  6,  will  be  well  hardened; 

No.  7  about  hard  enough  for  tap  teeth; 

No.  8  not  hardened. 

In  breaking  off  the  pieces,  which  should  be  done  over  the 
corner  of  an  anvil  and  the  pieces  caught  in  a  clean  keg  or  box  to 
keep  the  fractures  clean  and  bright,  it  will  be  found  that: 

No.  i  will  be  as  brittle  as  glass; 

No.  2  will  be  nearly  as  brittle; 

Nos.  3,  4,  5  will  break  off  easily,  each  a  little  stronger  than' the 
other; 

Nos.  6,  7  will  be  very  strong,  and  much  stronger  than  No.  8, 
or  the  bar  unhardened. 

Place  the  pieces  in  the  order  of  their  numbers,  fitting  the 
fractures,  then  "up-end"  each,  beginning  with  No.  i  and  follow- 
ing the  order  in  which  they  lie,  and  the  result  will  be  the  series  of 
fractures,  each  differeing  from  the  other. 

No.  i  will  be  coarse,  with  a  yellowish  cast,  and  very  lustrous; 

No.  2  will  be  coarse  and  not  quite  as  yellow  as  No.  i ; 

No.  3  will  be  finer  than  Nos.  i  or  2,  and  coarser  than  No.  8,  and 
will  have  a  fiery  luster; 

No.  4  will  resemble  No.  3  in  color  and  luster,  with  somewhat 
finer  grain,  and  will  be  coarser  than  No.  8; 

No.  5  will  be  about  the  same  size  as  No.  8,  but  will  have  fiery 
luster; 


2 1 6  HEAT  TREATMENT 

No.  6  will  be  much  finer  than  No.  8,  will  have  no  fiery  luster,  will 
be  hard  through  and  very  strong.  This  is  what  is  called  refined 
by  hardening. 

No.  7  will  be  refined  and  hard  on  the  corners  and  edges,  and 
rather  coarser  and  not  quite  so  hard  in  the  middle.  This  is 
about  the  right  heat  for  hardening  taps,  milling  tools,  etc.,  the 
teeth  of  which  will  be  amply  hard  while  there  will  be  no  danger  of 
•  cracking  the  tool. 

No.  8  illustrates  the  original  grain  of  the  bar. 

What  is  known  as  AUing's  test  is  very  similar  to  Metcalf's 
experiment:  A  bar,  with  a  longitudinal  slot  cut  on  each  side, 
is  heated  in  much  the  same  way,  and  after  quenching  is  broken 
along  the  slot  exposing  a  continuous  fracture  showing  the  effect 
of  the  varying  temperature. 

Grain  Growth  as  Affected  by  Strain.— It  was  found  by  Stead 
in  1898  that  iron  or  very  low  carbon  steel  with  less  than  about 
0.15  %  carbon,  when  heated  for  a  very  long  time  (hours  or  days) 
to  between  500  and  750°  C.  (930  and  1380°  F.),  the  grains  greatly 
increased  in  size  and  the  metal  became  brittle  (hence  called 
Stead's  brittleness) .  In  1912  Sauveur  experimented  with  some 
0.05%  carbon  steel  which  he  heated  or  "annealed"  at  650°  C. 
(1200°  F.)  for  7  hours,  after  making  an  impression  with  a 
Brinell  machine.  In  regard  to  his  conclusions  he  states  (Metallog. , 
266):  "These  observations  point  to  the  conclusion  that  ferrite 
grains  will  not  grow  on  annealing  below  the  critical  range  unless 
they  have  been  subjected  to  a  certain  stress  creating  a  certain 
strain,  and  that  they  will  not  grow  if  that  stress,  and  therefore 
the  resulting  strain,  has  been  exceeded.  In  other  words,  they 
point  to  the  existence  of  a  critical  strain  producing  growth, 
strains  of  greater  .»or  less  magnitude  being  ineffective.  The 
narrow  region  occupied  by  the  critically  strained  metal  should 
also  be  noted  as  well  as  the  very  sharp  line  of  demarcation  be- 
tween the  critically  strained  and  the  understrained  metal. 
The  separation  of  the  critically  strained  from  the  overstrained  is 
not  so  sharp."  The  critical  strain  is  also  referred  to  as  critical 
deformation,  Sauveur's  critical  strain,  and  Howe  refers  to 
"Sauveur's  process  of  coarsening  ferrite  by  heating  it  to  below 
AZ  after  a  critical  degree  of  plastic  deformation." 

As  a  result  of  his  investigations  on  this  subject,  Chappell 
(/.  /,  6*  S.  /.,  1914,  465)  draws  the  conclusions  as  to  the  changes 
involved  in  the  recrystallization  of  severely  worked  ferrite: 

(a)  Up  to  350°  C.  no  visible  reorganization  takes  place. 

(b)  From  350  to  500°  C.  potential  recrystallization  takes  place 
in  the  shape  of  disintegration  of  the  deformed  crystals  into  what 
has  been  termed  crystal  debris.     This  is  stage  I. 

(c)  Below  500  to  570°  C.  new  crystals  are  formed  among  this 
Crystal  debris,  which  new  crystals  grow  rapidly  from  almost 
ultramicroscopic  dimensions  into  normally  shaped  allotrimorphic 
crystals  easily  visible  at  high  magnifications.     This  is  stage  II. 

Grain  Size  and  Mechanical  Refining. — For  the  economical 
production  of  various  shapes  and  sections  by  rolling  or  forging, 
it  is  essential  to  heat  the  metal  to  a  relatively  high  temperature 


HEAT  TREATMENT 


217 


1400 


so  it  may  be  as  soft  and  ductile  as  possible.  If  the  metal  were 
simply  cooled  from  such  a  temperature  it  would  be  coarse- 
grained, and  the  cohesion  between  the  grains  would  be  weakened. 
This  would  mean  increased  brittleness  and  decreased  resistance 
to  shock,  which  would  render  the  material  unsuitable  for  many 
purposes. 

However,  when  mechanical  working  occurs,  the  grains  are 
reduced  to  a  size  dependent  chiefly  upon  the  temperature  at 
which  this  work  ceases  and,  in  a  somewhat  less  degree,  upon  the 
size  or  mass  of  the  piece,  it  being  of 
course  supposed  that  the  work  affected 
the  entire  section.  The  explanation  for 
this  is  readily  appreciated  by  referring  to 
Fig.  26  (also  due  to  Howe).  The  grains 
or  crystals  of  iron  in  their  normal  condi- 
tion are  equiaxed  and  belong  crystallo- 
graphically  to  the  isometric  or  cubic 
system,  that  is,  their  three  axes  are  at 
right  angles  to  each  other  and  of  equal 
length.  When  the  length  of  a  piece  is 
increased  by  rolling  or  forging,  there 
must  be  a  proportional  decrease  in  the 
cross-sectional  area.  The  small  grains  or 
crystals  which  make  up  the  structure 
must  be  deformed  to  at  least  the  same 
degree.  This  produces  a  condition  of 
unstable  crystallographic  equilibrium, 
since  the  axes  are  of  unequal  length 
(inequiaxed).  To  regain  the  normal  state 
each  grain  tends  to  split  up  into  several 
grains  of  smaller  size,  depending  upon 
the  shortest  axis  which  limits  that  of  the  other  two.  At  the 
relatively  high  temperatures  ordinarily  employed  for  mechanical 
working,  the  molecules  have  sufficient  freedom  of  movement  to 
bring  this  about. 

The  curve  Ac\A  is  the  grain-size  curve  of  Fig.  25  just  discussed. 
If  a  piece  of  steel  at  a  temperature,  and  with  corresponding 
normal  grain  size,  as  at  A,  is  sufficiently  deformed  by  a  single 
operation  of  mechanical  working,  the  grain  size  will  be  reduced 
from  A  to  B,  equal  to  OH.  If  the  piece  could  then  be  cooled 
instantaneously,  this  size  should  be  preserved.  Under  ordinary 
circumstances,  however,  the  cooling  requires  some  time.  In  this 
case  the  grain  size,  being  below  the  normal  for  the  existing 
temperature,  increases  progressively  toward  that  normal  size. 
Unless  interrupted,  the  cooling  of  the  piece  and  the  increase  in 
grain  size  from  B  is  along  the  curve  BCE.  After  crossing  the 
curve  Ac\A  no  change  in  the  grain  size  takes  place,  as  already 
explained  in  connection  with  Fig.  25.  The  final  size  is  conse- 
quently OE. 

If,  however,  when  C  is  reached,  mechanical  working  is  again 
applied,  the  grain  is  reduced  to  D.  By  further  repetitions  of 
cooling  and  working  the  zig-zag  curve  ABCDG  is  followed 


OHP    O 

Grain  -  Size 

FIG.  26. — Mechani- 
cal refining.  (Howe, 
"Iron,  Steel  and  Other 
Alloys.") 


2 1 8  HEAT  TREATMENT 

until  G  is  reached.  If  this  is  the  finishing  temperature,  the 
growth  of  the  grain  proceeds  until,  with  the  temperature  steadily 
falling,  the  curve  Ac\A  is  crossed,  but  this  time  at  a  much  lower 
point  than  before,  the  final  grain  size  being  OP. 

It  will  thus  be  seen  that  for  pieces  of  the  same  size,  that  is, 
with  the  same  rate  of  cooling,  the  grain  size  will  depend  upon  the 
finishing  temperature. 

Theoretically,  it  would  be  desirable  to  finish  just  above  Ac\. 
but,  owing  to  the  rapidly  diminishing  ductility,  this  is  usually 
not  practicable  because  of  the  danger  of  breaking  or  overtaxing 
the  rolls  or  hammer,  or  of  producing  excessive  strains  in  the 
material  itself.  This  last  is  especially  true  if  the  piece  is  of 
very  irregular  section,  since  the  molecules  have  lost  much  of 
their  freedom  of  movement. 

As  a  general  proposition,  the  finest  grain  must  be  secured  by 
reheating,  because  the  piece  can  then  be  held  a  sufficient  length 
of  tihie  at  the  proper  temperature  to  enable  the  necessary  re- 
arrangement of  the  molecules  to  occur,  which  is  not  possible  with 
mechanical  working  because  the  temperature  is  constantly 
falling. 

If  the  grain  size  of  two  pieces  of  steel  of  the  same  size  are 
compared,  one  of  which  was  worked  from  a  higher  temperature 
and  allowed  to  cool,  and  the  other  reheated  to  the  same  tempera- 
ture and  similarly  cooled,  the  grain  size  of  the  first  piece  is  the 
smaller  unless  the  cooling  is  extremely  slow;  and  the  faster  the 
cooling  the  greater  the  difference.  The  explanation  for  this  is 
because  the  final  working  reduced  the  size  to  below  what  was 
normal  at  that  temperature  and  the  temperature  had  fallen  con- 
siderably before  the  grain  was  of  correspondingly  normal  size; 
with  the  second  piece  the  heating  was  slow  enough  to  permit  of 
a  much  nearer  approach  to  the  normal  correspondence  between 
grain  size  and  temperature. 

Combined  Treatment  for  Grain  Size  and  Carbon.— From  the 
preceding  it  will  be  seen  that  there  can  be  secured  by  suitable 
heat  treatment  any  one  of  the  following  possible  combinations : 

1.  Grain  size  either  (a)  fine  or  (6)  coarse,  with 

2.  Carbon  either  (c)  in  solution  (homogeneous)  or  (d)  precipi- 
tated (heterogeneous) ;  and  for  2  ( d}  only,  with 

3.  Microscopic  segregation  either  (e)  fine  or  (0  coarse. 
Having  taken  up  separately  the  various  conditions  which  are 

met,  we  can  now  consider  how  heat  treatment  can  be  employed 
to  obtain  the  best  results.  To  this  end  we  secure  as  far  as  possible : 

1.  A  fine  grain  size. 

2.  Fine  and  uniform"  distribution  of  the  carbon  and  allied 
constituents. 

Only  in  the  case  of  a  eutectoid  steel  can  this  combination  be  met 
by  simple  treatment.  Assume  the  complicated  case  of,  say,  a 
°'5o%  carbon  steel  in  an  ordinary  condition  which  is  to  be  made 
as  soft  as  possible,  and  with  the  carbon  in  a  fine  state  and  uniformly 
distributed;  after  this  the  simpler  cases  can  be  readily  determined. 
Such  a  steel  as  received  will  have  been  slowly  cooled  after  rolling 
or  forging.  Its  structure  consequently  will  be  composed  of 


HEAT  TREATMENT  2 1 9 

relatively  coarse  grains  of  pearlite  surrounded  by,  or  interspersed 
in  envelopes  or  bands  of  excess  ferrite,  the  latter  being  expelled  in 
cooling  through  the  critical  range  between  -4r3-2,  and  Ar\  (OS 
and  PS  in  Fig.  38,  page  271).  The  following  procedure  is  then 
followed  which,  except  for  complications  frequently  encountered 
which  must  be  specially  handled,  will  approximate  the  desired 
results:  « 

1.  Heat    (at   any   rate    of   speed    consistent   with    uniform 
heating)  somewhere  above  Ac3,  and  cool  rapidly.     Heating  to 
above  Aci  would  be  sufficient  to  convert  the  eutectoid  portion 
into  a  solid  solution,  but  the  higher  temperature  is  necessary 
to  effect  solution  of  the  excess  ferrite;  rapid  cooling  preserves 
the  homogeneous  condition.     The  metal  is  then  homogeneous  in 
composition  but  is  hard  and  coarse  grained. 

2.  Heat  rapidly  just  above  Ac\  and  cool  rapidly.     The  heat- 
ing below  Aci  causes  precipitation  of  carbide,  and  by  passing 
above  this  point  the  cementite  and  ferrite  in  eutectoid  proportions 
are  converted  into  a  solid  solution;  the  excess  ferrite  is  not  (or  only 
very  slightly)  affected,  but  it  is  scattered  throughout  the  mass  in 
minute  fragments,  and  not  as  continuous  bands,  hence  is  in  the 
least  injurious  condition;  the  rapid  heating  and  cooling  tend  to 
prevent  microscopic  segregation.     The  metal  is  partly  homoge- 
neous and  partly  heterogeneous,  still  relatively  hard,  but  with  a 
fine  grain. 

3.  Reheat  rapidly  to  slightly  below  A Ci  and  cool  rapidly.     The 
solid  solution  of  eutectoid  is  converted  into  pearloid  and  the 
rapid  heating  and  cooling  (as  before)  tend  to  discourage  segrega- 
tion; the  rapid  cooling  from  below  Ac\  does  not  cause  hardening. 
The  metal  is  now  soft,  necessarily  heterogeneous  but  the  cemen- 
tite and  ferrite  are  as  uniformly  and  finely  distributed  as  possi- 
ble.   Q.E.F. 

Effect  of  Mass  on  Physical  Condition  and  Properties. — In 
what  has  gone  before  it  has  been  assumed  that  the  piece  has  been 
small,  that  is,  without  appreciable  mass,  and  in  most  discussions 
this  question  is  ignored. 


FIG.  27. — Manner  of  transmission  of  heat.     (Tiemann.) 

In  practically  all  experiments  which  have  furnished  the  infor- 
mation we  at  present  possess,  relatively  very  small  pieces  were 
employed.  It  is  possible  to  heat  or  cool  such  pieces  nearly 
uniformly  throughout,  about  as  rapidly  as  desired.  When, 
however,  the  attempt  is  made  to  put  into  practice  the  principles 
so  obtained,  it  is  found  that  a  new  factor  enters  largely  into  the 
problem,  namely,  the  mass  of  the  object  treated.  For  example, 
if  a  piece  of  fine  wire  is  heated  and  then  exposed  to  air  at  the 


220  HEAT  TREATMENT 

ordinary  temperature,  it  will  be  cooled  almost  instantaneously, 
while  the  time  required  in  the  case  of  a  large  shaft,  even  when 
plunged  into  cold  water,  will  be  many  minutes. 

Under  similar  conditions  the  rate  of  heating  and  cooling  is 
much  less  for  a  large  than  for  a  small  section,  for  two  reasons: 

i.  Because  the  distance  to  be  traversed  between  the  surface 
and  the  center,  in  the  absorption  or  dissipation  of  heat,  is 
greater.  This  rate  progressively  decreases  as  the  temperature 
of  the  body,  or  of  one  portion  of  the  body  in  relation  to  another 
portion,  approaches  that  of  the  source  of  heat  or  refrigeration,  in 
accordance  with  one  of  the  fundamental  laws  of  thermodynamics. 
Fig.  27  is  intended  to  illustrate  how  the  transference  of  heat  occurs 
between  different  portions  of  the  surface  and  the  interior.  AB- 
CD  is  a  section  through  an  object  uniformly  heated  or  cooled 


Rati< 

Diameter    Relative    Relative      Area  fr 
of  circle        Circum.       Areas        Circum 
i  i  i  i 

2242 
3393 

4  4  16  4 

5  5  25  5 

6  6  36  6 

7  7  49  7 

8  8  64  8 

9  9  8l  9 
IO            *     IO              100                  10 

FIG.  28 — Relative  Amounts  of  Heat  Trans 
mitted  per  Unit  of  Area  of  Surface.— 
(Tiemann.) 


on  all  sides.  The  transference  of  heat  to  ABFE  is  through  AB; 
to  A  ED  through  A  D,  etc.  The  progressive  effect  is  indicated 
by  the  dotted  lines  which  are  rounded  at  the  corners  of  the 
section,  because  in  those  regions  it  is  obtained  from  two 
sides. 

2.  Because  the  cross-section  increases  directly  as  the  square 
of  the  diameter,  while  the  circumference  increases  only  in  simple 
proportion  to  the  diameter.  The  same  relation  also  exists 
between  surface  and  volume  (mass),  since  these  are  obtained  by 
multiplying  the  circumference  (or  perimeter)  and  the  area, 
respectively,  by  the  same  value  representing  the  length.  In 
Fig.  28  is  a  table  of  ratios  between  circumference  and  area  for 
circles  of  diameters  of  i  to  10.  In  the  same  figure  are  shown 
three  circles  with  diameters  of  i,  2  and  4.  The  hatched  portions 
show  graphically  that  the  same  linear  distance  on  the  circum- 
ference of  each  must  serve  for  the  transfer  of  amounts  of  heat 
which  are  respectively  i,  2  and  4;  as  already  explained  these 
ratios  are  the  same  if  the  surfaces  and  volumes  (masses)  are 
substituted. 


HEAT  TREATMENT 


221 


This  may  be  summarized  in  the  following  general  law  for  the 
transference  of  heat : 

For  bodies  of  similar  section  the  amount  of  heat  transferred  per 
unit  of  surface  is  directly  proportional  to  the  ratios  of  their  dia- 
meters (or  similar  dimensions  of  their  cross-section). 

The  preservation  in  the  cold  state  of  the  condition  which 
existed  at  the  temperature  to  which  an  object  is  heated  (above 
the  critical  point)  is  dependent  upon  a  certain  rate  of  cooling, 
irrespective  of  the  size  or  mass  of  that  object.  .  With  the  means 
at  our  command  it  will  readily  be  appreciated  that  a  point  is 
very  quickly  reached  when  no  method  of  cooling  can  compensate 
for  the  increase  in  mass,  so  that  the  rate  of  cooling  decreases  with 
corresponding  increase  in  the  actual  time  required. 


Ductility 

FIG.  29. — Diagram  used  for  discussing  effect  of  mass. — (Tiemann.) 

As  a  direct  result  the  interior  of  large  masses  will  be  cooled  so 
slowly  as  to  have  only  the  properties  of  smaller  masses  cooled  in 
the  same  time,  or,  in  other  words,  the  effect  has  been  that  of 
annealing  rather  than  of  quenching,  as  these  terms  are  com- 
monly understood.  The  exterior  portion,  although  considerably 
retarded  in  its  cooling  by  the  necessary  transfer  through  it  of 
heat  from  the  interior  will  be  benefited  in  proportion  to  the  rate 
at  which  its  temperature  was  brought  below  the  critical  range, 
the  properties  of  different  portions  of  such  a  piece  being  in  inverse 
proportion  to  the  distance  from  the  surface. 

Fig.  29  is  intended  to  show  this  state  of  affairs  graphically, 
but  without  any  claim  as  to  its  quantitative  or  even  its  qualitive 
accuracy.  It  is  based  on  the  quality  formula  Q  =  S  X  D 
given  on  page  341.  The  curve  AB  is  supposed  to  represent 
the  maximum  theoretical  relation  between  strength  and  duc- 
tility for  steel  of  any  given  composition;  steels  of  other 
composition  would  be  represented  by  curves  varying  pro- 
gressively from  one  another.  If  it  be  tentatively  admitted 
that  this  curve  is  correct,  then  a  piece  with  the  properties  corre- 
sponding to  the  point  A,  with  relatively  high  strength  and  low 


222  HEAT  TREATMENT 

ductility,  would  be  of  equal  merit  with  another  piece  with 
properties  B,  where  relatively  low  strength  is  combined  with  high 
ductility;  or  with  a  piece  with  properties  represented  by  any 
other  point  on  the  curve,  since  the  curve  is  drawn  on  the  assump- 
tion of  a  constant  value  for  the  relation  between  strength  and 
ductility. 

If  a  piece  had  only  the  properties  C,  the  strength,  according 
to  our  assumption,  could  be  increased  to  C',  the  ductility  remain- 
ing the  same;  or  the  ductility  could  be  increased  to  C",  the 
strength  remaining  the  same;  or  any  other  maximum  relation 
could  be  attained,  as  C'",  on  the  curve  A  B. 

In  actual  practice  or  experiment,  however,  the  factor  of  mass 
is  bound  to  enter  in,  even  with  the  smallest  obtainable  section,  so 
that  this  maximum  curve  can  only  be  approached  but  never 
quite  reached.  With  very  small  pieces  the  experimental  maxi- 
mum might  be  as  represented  by  the  curve  A'  B';  other  curves 
A"  B",  A"'  B'",  etc.,  would,  in  the  same  manner,  represent 
the  possible  maxima  which  could  be  attained  by  pieces  of  in- 
creasing section. 

If  the  point  C,  for  example,  represents  the  properties  of  a 
large  untreated  section,  these  could  probably  be  improved  by 
annealing  to  some  point  E,  or  by  quenching  and  tempering  to  F 
or  G.  With  cooling  more  rapid  than  usual,  as  by  quenching  in 
iced  brine  or  liquid  air,  followed  by  tempering,  the  point  D  might 
be  reached. 

The  reason  for  the  higher  relation  of  properties  in  a  small 
section  over  that  in  a  large  section,  treated  under  the  same 
conditions,  would  appear  to  be  due  principally  to  the  condition 
of  the  carbon.  This  is  also  borne  out  by  the  difference  in  the 
properties  of  test  specimens  cut  respectively  from  near  the 
surface  and  at  the  center  of  large  sections,  which  has  resulted  in 
the  clause  in  forging  specifications  that  "the  axis  of  the  specimen 
shall  be  located  at  any  point  one-half  the  distance  from  the 
center  to  the  surface  and  shall  be  parallel  to  the  axis  of  the  object 
tested,"  with  a  view  to  determining  the  average  values. 

Effect  of  Mass  on  Strains  Produced  in  Heat  Treatment. — Un- 
der suitable  conditions  of  heating  it  is  possible  to  secure  a  reason- 
ably uniform  temperature  throughout  a  fairly  large  section.  If 
the  rate  of  cooling  could  then  be  controlled  so  that  a  large  section 
could  be  cooled  as  rapidly  (that  is,  in  the  same  time)  as  aAsmaller 
object,  the  uniformity  of  the  material  in  the  two  cases  should  be 
the  same.  As  a  matter  of  fact,  however,  such  a  state  of  affairs 
cannot  be  attained,  as  the  conduction  of  heat  from  the  center 
to  the  outside  of  a  section  of  any  size  is  relatively  slow  for  the 
reasons  already  given,  and  cannot  be  hastened  sufficiently  by  any 
means  at  our  command.  Even  if  such  were  not  the  case,  there  is 
another  insurmountable  obstacle  -  in  the  path.  This  is  the 
possible  introduction  of  excessive  strains  in  large  pieces,  par- 
ticularly where  there  is  any  irregularity  of  section.  Rupture  or 
incipient  cracks  resulting  from  this  would  not  be  corrected 
by  any  heat  treatment  alone.  Such  cracks  from  irregular 
contraction  due  to  unequal  cooling,  are  termed  treatment  cracks, 


HEAT  TREATMENT 


223 


heat  treatment  cracks,  cold  cracks,  etc.  (see  Cracks,  p.  no); 
clinking  is  an  English  term  to  describe  the  sound  when  material 
cracks  from  irregular  expansion  due  to  too  rapid,  i.e.,  unequal 
heating.  Fig.  30  is  intended  to  illustrate  how  such  cracks  or 
strains  can  develop  when  a  large  object  is  too  rapidly  cooled  by 
quenching  or  otherwise.  For  simplicity,  only  linear  expansion 
and  contraction  at  one  end  are  considered.  A  BCD  is  the 


Compression^  B   g"  B' 


\D                — 

IF                                         E 

Tension  ' 

&  Compression' 

FIG.  30. — Method  of  development  of  quenching  strains  and  cracks. 
(Tiemann.) 

original  length  when  free  from  all  strains.  AB'C'D  is  the 
length  when  heated  to  the  quenching  temperature.  If  the 
cooling  is  progressively  slower  from  outside  to  center,  and  each 
successive  layer  is  deformed  in  length  by  the  obstruction  to  full 
contraction  offered  by  the  interior  layers,  the  appearance  of  the 
piece  would  be  as  shown  by  the  curve  B'EC' ',  provided  each 
layer  could  assume  its  new  length.  However,  as  they  are  all 
firmly  bound  together,  the  piece  will  assume  the  intermediate 
rectangular  section  AB"C"D.  The  strains  vary  from  maxi- 


FIG.  31. — Internal  quenching  crack.    (Tiemann.) 

mum  compression  at  the  outside  to  maximum  tension  at  the 
central  axis.  If  this  latter  strain  exceeds  •  the  elastic  limit, 
the  central  portion  must  stretch  and  may  go  far  enough  to  de- 
velop a  crack,  particularly  if  some  flaw  already  existed,  thereby 
upsetting  the  equilibrium  of  forces.  The  crack  will  then  con- 
tinue to  spread  until  nearly  all  the  strains  have  been  released. 
Such  an  internal  quenching  crack  is  shown  in  Fig.  31  (based  on 


224  HEAT  TREATMENT 

actual  cases  of  service  failures).  The  shaded  portion  shows  the 
original  extent  of  the  crack;  the  sound  (unshaded)  portion  was 
insufficient  to  withstand  the  shocks  and  stresses  in  service. 
H.  Le  Chatelier  (/.  /.  &•  S.  I.,  1914, 1,  247),  in  discussing  causes  of 
rupture  in  hardening  by  quenching,  says  that  while  he  does  not 
deny  the  possibility  of  the  two  causes  from  irregular  distribution 
of  temperature  during  quenching,  and  differences  in  expansion 
caused  by  non-uniform  hardening,  there  is  a  third  cause  which  is 
more  frequent  and  more  important.  "At  the  moment  of  the 
transformation  of  the  austenite  into  martensite,  that  is,  gamma 
into  alpha  iron,  in  the  solid  solution,  a  sudden  and  considerable 
increase  in  volume  occurred.  That  transformation  did  not  take 
place  at  every  point  within  the  mass  at  the  same  moment.  At 
each  point  at  which  it  occurred,  there  were  developed,  momen- 
tarily, enormous  stresses  which  led  to  cracking.  After  cooling 
they  ultimately  reached  the  same  state." 

Density  as  Affected  by  Heat  Treatment— "E.  H.  Schulz  has 
studied  the  changes  of  volume  and  form  of  steel  due  to  heat 
treatment,  a  subject  concerning  which  little  exact  knowledge 
exists.  The  following  is  a  summary  of  the  author's  main  con- 
clusions. In  annealing,  the  density  of  carbon  steel  decreases  as 
the  carbon  percentage  increases,  but  the  decrease  is  not  regular, 
and  an  irregularity  occurs  with  0.5%  of  carbon.  By 
quenching,  the  density  is  decreased  by  an  amount  which  is  greater 
as  the  carbon  increases.  Below  800  to  900°  C.  the  volume  in- 
creases rapidly  as  the  quenching  temperature  is  raised,  but  above 
that  range  the  quenching  temperature  has  little  effect  on  the  den- 
sity. In  the  case  of  high-carbon  steels,  quenching  in  water  always 
confers  greater  density  than  quenching  in  oil,  the  difference  being 
most  marked  in  steel  containing  the  eutectbid  proportion  of  car- 
bon. The  original  density  of  the  steel  is  never  restored  by 
annealing  after  quenching,  but  the  difference  of  density  in  the  two 
states  can  be  reduced  by  successive  quenching  and  annealing. 
Electrolytic  copper  and  electrolytic  iron  tempered  at  150°  C.  both 
show  a  large  increase  in  density,  due  to  irregularities  of  a  purely 
physical  nature,  and  the  density  is  considerably  influenced  by  the 
rate  of  cooling  after  tempering.  The  density  of  quenched  steel  is 
increased  on  tempering  by  an  amount  increasing  with  the  carbon. 
The  density -tempering  temperature  curves  are  very  irregular,  but 
all  show  a  maximum  at  430°  C.  (810°  F.). 

"In  alloy  steels  the  difference  in  density  as  between  water- 
hardened  and  oil-hardened  steels  is  not  so  great  as  in  the  case  of 
ordinary  carbon  steels.  Quenched  alloy  steels  show  no  maximum 
at  430°  C.,  but  from  that  temperature  upward  the  density  in- 
creases continually.  Eutectoid  steels  tend  more  than  others  to 
develop  hardening  cracks,  on  account  of  their  greater  volume 
changes  during  quenching.  Bars  increase  in  length  according  to 
the  carbon  content,  and  the  increase  is  proportional  to  the  length 
of  the  bar. 

"  When  quenched  from  960°  C.  (i  760°  F.)  in  water  several  of  the 
special  steels  always  gave  hardening  cracks,  so  that  the  specific 
gravity  could  not  be  determined.  The  nickel  and  chromium 


HEAT  TREATMENT  225- 

steels  show  a  smaller  increase  in  volume  with  quenching  than 
plain  steels  of  the  same  carbon  content 

"This  is  also  true  of  the  manganese  steels,  although  not  to  so 
great  an  extent,  while  the  chromium-nickel  steels  shows  a  pro- 
•portionally  great  change  of  volume.  Although  these  results 
do  not  apply  to  all  special  steels,  yet  it  is  certain  that  through 
suitable  special  additions  the  change  in  volume  due  to  quenching 
can  be  greatly  reduced. 

"The  author  considers  that  the  change  in  volume  brought  about 
by  quenching  steel  is  only  small  if  the  quenching  temperature  be 
within  a  limit  close  to  the  critical  temperature.  Very  great 
changes  in  volume  are  brought  about  if  this  limit  is  even  slightly 
exceeded"  (Abstr.  from  Zts.  Ver.  deuL  Ing.  in  /.  /.  &"  S.  /., 
1915,  II,  303-4)-. 

The  increase  in  volume  from  quenching  is  due  not  simply  to 
quenching  strains  but  also  to  the  change  in  density  of  steel  from 
one  allotropic  variety  of  iron  to  another.  The  temperature- 
density  curve  shows  at  first  a  regular  decrease  of  density  on 
heating,  then  a  sudden  reversal  through  a  certain  range  (corre- 
sponding closely  with  the  critical),  changing  back-  again  to  a 
progressive  decrease  above  this.  Based  on  researches  along  these 
lines  the  Packard  Motor  Company  has  devised  a  process  whereby 
they  are  able  to  (a)  increase,  (b)  decrease,  or  (c)  maintain  constant 
the  size  of  an  object  by  selecting  the  suitable  quenching  tempera- 
ture as  demonstrated  by  means  of  a  round  plug  machined  so  it 
will  barely  pass  through  a  corresponding  hole  in  a  plate. 

It  should  be  appreciated  that  where  increase  of  volume  occurs 
an  object  tends  to  assume  a  spherical  form  which  is  known  to 
possess  the  minimum  superficial  area  for  a  given  volume.  As  an 
illustration  of  this  fact,  a  high-carbon  die  used  in  wire  drawing, 
which  was  originally  cylindrical,  after  say  a  hundred  or  more 
quenchings  (for  the  purpose  of  restoring  the  hole),  became  nearly 
spherical.  This  accounts  for  the  slight  shortening  observed 
in  cylindrical  objects,  such  as  shafting,  after  quenching  operations, 
provided  excessive  longitudinal  strains  were  not  set  up  sufficient 
to  cause  actual  rupture,  and  which  were  largely  removed  by  sub- 
sequent reheating. 

We  are  therefore  confronted  with  the  contradictory  state  of 
affairs  that  the  larger  the  section  the  more  vigorous  should  be  the 
cooling;  and  the  more  vigorous  the  cooling  the  greater  the  liability 
to  excessive  strains  or  rupture.  While  the  component  particles 
of  the  .material  may  be  advantageously  affected,  the  object  as  a 
whole  suffers.  From  this  it  is  evident  that  for  any  given  size 
or  section  there  is  a  maximum  relation  between  ductility  and 
strength,  which  decreases  as  the  dimensions  increase;  that  if 
the  strength  is  maintained  constant  the  ductility  must  decrease, 
and  vice  versa,  as  discussed  in  connection  with  Fig.  29. 

It  must  consequently  be  realized  that  the  possibilities  as  re- 
gards the  physical  properties  of  large  sections  are  not  so  great  as 
in  the  case  of  small  sections,  and  this  must  be  taken  into  considera- 
tion in  drawing  up  physical  requirements.  For,  restating  the 
case  briefly,  under  similar  circumstances: 
15 


226  HEAT  TREATMENT 

1.  The  condition  of  the  carbon  and  the  grain  size  depend  upon 
the  temperature  and  the  rate  of  cooling. 

2.  The  rate  of  cooling  depends  upon  the  diameter  or  thickness 
of  a  given  section,  and  probably  also  to  a  certain  extent  upon  the 
length,  or,  in  other  words,  upon  the  mass. 

3.  The  rate  of  cooling  through  the  critical  range,  and  just 
below  the  lower  critical  point,  is  of  much  greater  importance 
than  during  any  subsequent  tempering  (after  quenching). 

To  determine  the  uniformity  of  heating,  the  temperature  musl 
be  of  unquestioned  accuracy.  Further,  the  rate  of  heating  must  be 
carefully  determined  by  experiment  to  secure  proper  penetration 
It  will  be  seen  that  the  principles  involved  are  comparatively 
simple.  The  main  difficulty  in  carrying  out  the  operation' 
commercially  is  found  in  securing  the  necessary  degree  of  uni 
formity.  It  is  for  this  reason  that  special  equipment  is  so  essen- 
tial. Of  equal  importance  is  the  proper  material,  the  compositior 
of  which  must  be  definitely  known,  as  variations,  particular!) 
in  carbon,  will  result  in  different  physical  properties  being  securec 
under  the  same  conditions  of  treatment. 

Overheating  and  burning  result  when  steel  or  iron  has  beei 
heated  to  a  very  high  temperature  which  is  respectively  moderatel) 
close  and  very  close  to  the  melting  point.  Both  these  effect: 
are  frequently  termed  overheating,  but  this  should  be  avoided 
The  overheating  zone  and  burning  zone  are  the  respective  range; 
of  temperature  where  these  effects  occur.  In  overheating  th( 
grain  is  rendered  very  coarse,  and  the  cohesion  between  the  grain; 
is  lessened  so  the  metal  is  tender;  the  normal  condition  can  b< 
restored  by  heat  refining  alone,  or  better,  in  combination  witl 
mechanical  working.  In  burning  the  condition  may  range  fron 
extreme  overheating  to  where  the  more  fusible  constituents  mel 
and  run  out  from  between  the  grains,  giving  rise  to  a  shower  o 
brilliant  sparks.  The  former  condition  can  probably,  at  leas 
partially,  be  corrected  by  heat  treatment  and  mechanical  work 
ing,  but  steel  in  the  latter  condition  is  hopelessly  ruined,  and  i: 
fit  only  to  be  remelted,  and  is  said  to  be  oxygenated.  If  higl 
carbon  steel  is  heated  for  some  time,  with  access  of  air,  to  a  tern 
perature  not  necessarily  high  enough  to  cause  overheating,  some 
of  the  carbon  becomes  oxidized,  and  the  steel  is  termed  roastec 
or  baked.  A  similar  steel,  repeatedly  heated  and  hardened 
in  time  acquires  a  brittle  exterior,  which  must  be  removed  t< 
restore  its  good  qualities,  and  when  in  this  condition  is  sometime: 
said  to  be  dead.  To  give  a  piece  a  short  heat  mean^  to  heat  i 
for  a  small  portion  of  its  length  only,  as  where  one  end  is  to  b« 
upset  or  swedged  in.  After  an  object,  especially  of  tool  steel 
has  been  heated,  particularly  for  a  long  time  and  at  a  high  tern 
perature,  there  is  a  skin  or  layer  just  beneath  the  scale,  which  i 
nearly  decarburized,  and  is  called  the  bark ;  this  layer  is  some 
times  as  much  as  an  eighth  of  an  inch  thick. 

Hardening. — This,  as  commonly  understood,  consists  in  impart 
ing  to  steel  an  appreciable  or  useful  hardness  for  which  a  suitabb 
grade,  i.e.,  a  composition  (principally  carbon  and  certain  specia 
elements)  which  lends  itself  to  this  purpose,  is  necessary.  It  ma; 


HEAT  TREATMENT  227 

include  cases  where  the  tensile  strength  and  elastic  limit  of  soft 
steels  are  raised,  but  the  line  is  roughly  drawn  to  include  such 
steels  as  can  be  made  very  resistant  to  abrasion,  indentation  and 
bending,  where  they  are  to  be  fashioned  into  cutting  tools, 
hammers,  drifts,  crow  bars,  bearing  parts,  agricultural  imple- 
ments, and  similar  objects.  Hardening  is  sometimes  secured  by 
cold  working,  by  which  means  a  temporary  cutting  edge,  for 
example,  may  be  given  to  even  the  softest  steel  or  iron,  but  is 
ordinarily  accomplished  by  heat  treatment  alone.  In  this  latter 
case,  with  which  we  are  concerned,  the  material  is  heated  to 
above  a  certain  critical  temperature  followed  by  rapid  cooling. 
The  degree  of  hardness  obtained  will,  in  general,  vary  directly 
with  (a)  the  percentage  of  carbon,  (b)  the  rate  of  cooling,  and 
(c)  the  temperature  above  the  critical  point  from  which  the 
cooling  takes  place.  If  the  object  is  very  small  it  may  be  suffi- 
cient to  remove  it  from  the  source  of  heat  and  expose  it  to  the 
air  or  a  blast  (air  cooling,  air  hardening,  and  particularly  if  a 
blast  is  used,  air  quenching),  but  as  a  rule  this  is  not  sufficiently 
rapid,  and  in  such  cases  the  article  is  plunged  into  some  liquid 
(quenching  bath  or  quenching  medium)  or  sometimes  sprayed  with 
it,  to  remove  the  heat  faster;  this  operation  is  known  as  quenching, 
quenching  hardening,  or  hardening,  qualified  properly  by  the  name 
of  the  medium  employed  (unless  clear  from  the  context),  e.g., 
water  hardening  (quenching) ;  lead  hardening  (quenching).  The 
term  cooling  is  also  used  in  the  same  manner,  as  water  cooling,  oil 
cooling,  air  cooling,  etc.  Water  quenching  is  rarely  called  water 
dipping.  The  temperature  to  which  the  object  is  heated  for 
quenching  is  referred  to  as  the  quenching  temperature.  The 
term  quenching  has  been  and  still  is  commonly  understood  to  con- 
note the  use  of  water,  in  the  sense  of  extinguishing,  as  a  fire,  or 
destroying  or  allaying,  as  thirst,  in  both  cases  as  with  red  hot 
iron  with  the  idea  that  this  was  secured  by  removing  heat.  This 
latter  meaning  has  most  strongly  persisted  in  the  case  of  heat 
treatment,  hence  the  extension  of  the  term  to  include  at  first 
liquid  media  other  than  water,  and  later  air,  etc.  While,  as  just 
stated,  quenching  now  properly  signifies  the  rapid  extraction 
of  heat,  and  is  therefore  commonly  used  in  the  same  sense  as 
hardening,  yet  manganese  steel  or  high-nickel  steel  (both  of  which 
are  austenitic),  for  example,  plunged  into  water  from  a  yellow 
heat,  are  quenched  and  toughened,  but  not  hardened;  this  par- 
ticular result  is  termed  water  tempering  or  water  toughening;  in 
contradistinction  the  ordinary  result  of  quenching  is  referred  to 
as  quenching  hardening.  Tempering  is  sometimes  employed  (but 
confusingly)  to  mean  the  same  as  hardening,  and  in  this  sense 
the  term  temperability  has  been  suggested  to  indicate  the  capa- 
bility of  steel  of  being  hardened. 

The  temperature  and  the  nature  of  the  liquid  determine  the 
rate  of  cooling,  and  also  the  temperature  to  which  the  object 
may  be  cooled.  There  is  no  inherent  or  peculiar  virtue  or  dif- 
ference, per  se,  in  any  one  medium  over  another,  except  what 
relates  to  the  respective  ability  to  extract  heat  and  so  affect  the 
rate  of  cooling;  in  other  words,  it  is  the  rate  of  cooling  which  is  at 


228  HEAT  TREATMENT 

all  times  responsible  for  the  results,  irrespective  of  the  means 
employed.  Iced  brine  and  cold  water  are  two  of  the  most  effective, 
and  oil  and  molten  lead  are  less  active  in  the  order  given.  Since 
the  effect  on  the  rate  of  cooling  of  the  two  last  is  not  so  great, 
being  similar  to  water  hardening  followed  by  tempering,  the 
operations  in  which  they  are  employed  are  frequently  called 
oil  tempering  and  lead  tempering,  but  the  terms  oil  hardening 
and  lead  hardening  are  preferable.  As  a  rule,  plain  carbon  steels 
where  actual  hardening  is  desired,  contain  carbon  over  0.60%; 
where  an  increase  in  strength  and  elasticity  is  desired,  without 
a  material  reduction  in  ductility,  for  axles,  shafts,  etc.,  the  carbon 
is  usually  between  0.35  and  0.60%.  The  temperatures  recom- 
mended by  the  A.  S.  T.  M.  for  annealing  operations  are  as  follows: 

Range  of  Carbon  Range  of  Annealing  Temperature 

Content 

Less  than  0.12%  875  to  925°  C. (1607-1697°  F.) 

o.i 2.  to- 0.29%  840  to  870°  C.  (1544-1598°  F.' 

0.30  to  0.49%  815  to  840°  C.  (1499-1544°  F. 

0.50  to  i  .00%  790  to  815°  C.  (1454-1499°  F. 

Double  hardening  consists  in  quenching  the  article  twice, 
usually  in  oil  or  water  (see  double  quenching,  page  233).  Double 
quenching  is  particularly  applicable  to  casehardened  objects 
consisting  of  a  low-carbon  core  with  a  high  critical  point,  and  a 
high-carbon  case  with  a  much  lower  critical  point :  by  a  prelimi- 
nary high  temperature  quenching  (regeneration  quenching)  the 
core  is  refined,  followed  by  quenching  from  a  lower  temperature 
suitable  for  the  core  (hardening  quenching).  Broken  harden- 
ing, specially  applicable  to  tools  of  irregular  section,  such  as  mill- 
ing cutters,  consists  in  quenching  in  water  until  the  disappearance 
of  color  and  then  transferring  to,  and  completing  the  cooling  in, 
oil.  Differential  or  decremental  hardening  (sometimes  called 
differential  cooling)  is  where  the  entire  object  is  heated  to  a 
hardening  temperature  but  only  a  portion  is  hardened  by  quench- 
ing. For  example,  a  common  method  of  hardening  chisels  is  to 
(a)  heat,  (b)  plunge  the  point  in  water  until  cold,  then  (c)  rub  one 
side  on  a  brick  or  piece  of  emery  paper  to  get  a  bright  surface,  (d} 
allow  the  heat  to  diffuse  from  the  still  hot  portion  until  the  proper 
temper  color  (see  below)  is  obtained,  after  which  (e)  the  whole 
piece  is  plunged  at  intervals  in  the  water  to  prevent  further  tem- 
pering, but  so  the  cooling  does  not  unduly  harden  the  back  part 
which  must  be  relatively  soft  and  tough.  About  the  same  result 
may  be  reached  by  differential  heating  (sometimes  called  flash 
heating),  whereby  only  the  portion  to  be  hardened  reaches  a 
temperature  above  the  critical,  when  the  whole  object  is  plunged 
in  the  quenching  bath.  If  the  piece  is  quenched  as  soon  as  the 
temperature  passes  the  critical  point,  and  is  still  rising,  it  is  called 
hardening  on  a  rising  heat.  Since  the  critical  point  on  cooling 
is  lower  than  on  heating,  it  is  possible,  after  the  temperature  has 
risen  above  this  to  hold  the  piece  in  air  (or  otherwise)  until  the 
temperature  is  slightly  above  the  recalescent  point  and  then 


HEAT  TREATMENT  .          229 

quench.  Also  at  a  temperature  slightly  above  what  is  neces- 
sary for  hardening,  there  will  be  greater  certainty  of  the  trans- 
formation being  complete.  The  hardening  effect  will  not  be  so 
great  as  in  the  former  case  but  the  lower  temperature  will  have 
less  tendency  to  set  up  injurious  strains;  this  is  called  hardening 
on  a  falling  heat.  Press  hardening  is  employed  for  thin  objects, 
such  as  saw  blades,  and  consists  in  pressing  the  heated  object  in  dies 
which  serve  both  to  harden  and  to  flatten  it.  The  dies  can  be  so 
shaped  as  not  to  come  in  contact  with  parts  which  are  not  to  be 
hardened.  Crocodile  skin  is  the  name  given  to  the  appearance 
resulting  from  oil  or  grease  on  the  surface  which  has  not  entirely 
burned  off  during  the  heating,  or  leaves  a  deposit  producing  a 
different  coloration. 

Special  Methods  of  Hardening. — Caron's  method  consists  in 
quenching  in  hot  water  (hot  water  hardening),  by  which,  owing 
to  the  slower  rate  of  cooling,  is  secured  an  effect  equivalent  to 
ordinary  hardening  plus  tempering;  except  with  small  pieces  con- 
taining high  carbon,  a  negative  quenching  effect  (see  below)  will 
result:  In  James  Chesterfield's  process  coiled  strips  or  tapes  are 
heated  in  a  box,  the  end  projecting  through  a  hole.  When  hot 
enough  they  are  pulled  out  and  passed  between  water-cooled 
blocks,  after  which  they  are  tempered  by  coating  with  oil  which 
is  burned  off.  In  Clemandot's  process  a  bar  of  steel  heated  to  a 
bright  cherry  is  subjected  to  great  pressure  between  the  faces  of  a 
hydraulic  press  (or  otherwise) .  It  was  claimed  that  the  steel  was 
thereby  rendered  harder  and  of  a  finer  grain  (refining  by  harden- 
ing) than  when  hardened  in  the  ordinary  manner.  This  is  some- 
times called  hardening  or  tempering  by  compression  or  pressure 
hardening.  It  closely  resembles  press  hardening  mentioned 
above.  By  the  Jarolimek  process  the  red-hot  steel  is  held  in  the 
comparatively  dense  center  of  a  spray  of  water  until  black,  and 
then  allowed  to  cool  in  the  outer  less  dense  portion  of  the  spray  at 
a  rate  which  is  claimed  to  be  controllable;  or,  if  the  object  is  of 
very  small  size,  in  the  air.  Chas.  Gill's  method  of  quenching 
was  to  use  easily  fusible  alloys,  such  as  lead  and  tin,  lead,  or  tin 
and  bismuth,  which  were  kept  at  such  a  temperature  that  a  sub- 
sequent tempering  operation  was  unnecessary.  Osmond  sug- 
gests molten  zinc  instead  of  lead  as  the  former  does  not  give  off 
noxious  fumes,  is  cheaper,  and  the  slightly  higher  melting  point 
should  be  more  than  offset  by  its  possessing  three  times  the 
specific  heat.  Ferret's  method  (later  studied  by  Jarolimek) was 
to  use  a  blast  of  air  loaded  with  water  vapor.  Reaumur's  process 
was  to  harden  the  points  of  tools  by  sticking  them  into  (and  let- 
ting them  melt)  solid  lumps  of  tin  or  lead.  He  also  suggested 
gold,  silver  and  copper  for  this  purpose.  Seguin's  process  con- 
sists in  quenching  steel,  heated  to  a  cherry  red,  in  either  (a)  dilute 
sulphuric  or  hydrochloric  acid,  or  (b)  in  a  mixture  of  turpentine 
and  water.  In  the  Terre-Noire  process,  projectiles  (which  were 
simply  cast  and  bored  out)  were  heated  to  a  red  heat,  the  point 
only  dipped  into  water  until  black,  and  the  whole  piece  then 
plunged  into  oil  and  kept  there  until  cold.  This  was  followed 
by  reheating  to  a  temperature  just  high  enough  to  remove  the 


230  HEAT  TREATMENT 

adhering  oil.  G.  Theodossief's  process  consists  in  quenching  in 
glycerine,  either  pure  or  mixed  with  different  proportions  of 
water,  and  sometimes  containing  certain  salts;  the  temperature 
may  also  be  varied  depending  upon  the  nature  of  the  steel  and 
upon  the  results  desired.  The  Tressider  process  (specially 
applicable  for  armor  plate)  consists  in  applying  the  quenching 
liquid  in  the  form  of  a  spray  to  one  or  both  sides  of  the  heated 
piece,  as  desired.  A  number  of  other  special  processes  have  been 
patented  and  suggested  from  time  to  time,  for  example :  the  utili- 
zation of  the  latent  heat  of  fusion  of  various  mixtures  of  water  or 
lime  with  ice,  or  of  ice  alone  (Schneider  et  Cie.) ;  easily  fusible 
alloys  and  salts;  water  covered  with  a  layer  of  oil.  Electric 
hardening  consists  in  heating  the  piece  by  means  of  its  resistance 
to  the  passage  of  an  electric  current,  or  by  an  electric  arc, 
after  which  it  is  quenched  as  usual.  Electricity  may  similarly 
be  employed  for  heating  to  a  lower  temperature  for  tempering 
(electric tempering).  The  Lagrange  and  Hoho  process  depends 
upon  the  fact  that  the  outer  portion  of  a  small  piece  of  steel, 
forming  the  negative  pole  in  an  electrolytic  solution,  may  be  heated 
to  a  bright  red  by  the  passage  of  an  electric  current  of  fairly 
high  voltage  and  low  amperage,  before  the  interior  is  sensibly 
affected;  if  the  current  is  then  interrupted,  the  electrolyte  will 
serve  as  a  quenching  bath. 

Tempering. — Also  called  letting  down,  drawing,  drawing  back, 
draw-tempering  and  toughening.  Tempering  is  always  preceded 
by  some  hardening  operation,  except  in  certain  special  cases  where 
hardening  and  tempering  are  combined  in  one  operation.  The 
action  which  causes  a  high  degree  of  hardening  at  the  same  time 
produces  a  considerable  amount  of  brittleness  and  concomitant 
strain,  and  tempering  signifies  the  mitigation  or  slight  reduction 
of  the  severity  of  the  hardening  operation  for  the  purpose  of 
removing  as  much  as  possible  of  the  brittleness  and  strain,  without 
affecting  the  hardness  more  than  is  unavoidable,  leaving  the  steel 
relatively  hard  and  tough,  instead  of  very  hard  and  brittle.  This 
is  the  earliest  and  preferable  meaning  of  tempering  as  employed 
particularly  for  cutting  tools  and  springs.  The  treatment 
necessary  consists  in  reheating  to  a  tempering  temperature  from 
about  200  to  300°  C.  (390  to  625°  F.)  depending  upon  the  pur- 
pose for  which  the  material  is  intended.  The  heating  may  be 
done  in  air  or  in  some  liquid,  and  the  temperature  may  be 
measured  by  a  thermometer  or  a  pyrometer,  or,  if  in  air,  by  the 
oxide  tints  (temper  colors  or  letting  down  tints)  which  form  on  a 
surface  freed  from  scale.  The  temperatures  and  names  (assigned 
by  H.  M.  Howe)  corresponding  to  the  various  colors  are  as  follows: 

Temper  color Degrees  C.  Degrees  F. 

Pale  yellow  or  straw  color 220  428 

Golden  yellow 243  469 

Purple : 277  531 

Bright  blue 288  550 

Dark  blue 316  601 


HEAT  TREATMENT  23 1 

It  should  be  appreciated  that  these  temper  colors  are  due  to  the 
thickness  of  the  oxide  film  causing  a  corresponding  interference 
of  light;  hence  holding  for  a  longer  period  serves  to  cause  a  thicker 
oxide  film  with  a  resulting  change  in  appearance.  The  effect 
of  time  on  tempering,  i.e.,  from  holding  at  a  given  temperature 
will  depend  somewhat  upon  the  temperature  itself  and  also  the 
degree  of  previous  hardening.  At  lower  temperatures  the  con- 
dition of  metastable  equilibrium  is  more  complete,  therefore,  the 
tendency  to  normal  equilibrium  is  greater. 

The  tempering  may  be  effected  in  the  case  of  small  objects  by 
a  heated  plate  (tempering  plate)  of  cast  iron  or  steel  upon  which 
the  objects  are  allowed  to  rest  until  they  reach  the  desired  tem- 
perature. Blazing  off,  burning  off,  or  oil  flaring  is  a  method  of 
tempering  sometimes  employed  for  springs,  etc.;  it  consists  in 
heating  the  object  coated  with  oil,  either  from  the  quenching 
bath  or  otherwise,  until  it  reaches  a  temperature  just  high  enough 
to  cause  the  oil  to  burn  readily  in  the  air. 

In  James  Horsfall's  process  for  tempering  steel  wire  for  pianos, 
etc.,  the  wire  was  drawn  to  nearly  the  desired  diameter,  heated 
to  redness,  and  quenched  in  water  or  oil.  It  was  then  plunged 
into  molten  lead;  etc.,  until  it  had  been  sufficiently  tempered, 
after  which  the  drawing  was  completed.  For  other  special 
methods  of  tempering  see  under  Hardening  (above)  and  Anneal- 
ing (below).  Pieces  quenched  in  a  bath,  maintained  at  the  tem- 
perature to  which  they  would  otherwise  be  reheated  if  quenched 
cold,  are  sometimes  said  to  be  mild  tempered  or  quasi  tempered. 

Annealing. — This  term  is  commonly  understood  to  mean  a  re- 
heating operation  followed  by  slow  cooling  to  effect  one  or  more 
of  the  following  objects:  (a)  completely  undoing  the  effect  of 
hardening  (either  thermal  or  mechanical),  leaving  the  steel  in  its 
softest  and  most  ductile  condition:  (6)  removing  any  strains  set  up 
by  too  rapid  cooling,  particularly  if  the  rate  has  been  different  in 
different  parts  of  the  piece:  and  (c)  refinement  of  the  grain.  For 
the  first  two  it  is  sufficient  if  the  annealing  temperature  is  below 
the  lower  critical  point,  say  not  over  about  600  to  650°  C.  (ino 
to  1200°  F.),  but  for  the  last  the  temperature  must  be  raised 
to  above  the  upper  critical  point,  except  in  special  treatments  pre- 
ceded by  quenching  as  described  below  (for  refining  temperatures 
see  table  on  page  228).  In  the  last  case,  also,  the  rate  of  cooling 
must  be  slow  until  the  temperature  is  below  the  critical  range, 
after  which  increasing  the  rate  has  no  effect  upon  the  hardening: 
but  as  rapid  cooling  is  liable  to  cause  strains,  particularly  in 
pieces  which  are  large  or  of  irregular  form,  it  is  generally  slow. 
At  times,  however,  to  hasten  the  operation,  when  the  object  has 
become  black  in  color  it  is  plunged  in  water,  which  is  termed 
water  annealing  or  negative  quenching.  Ordinarily  in  annealing 
the  temperature  is  carried  to  slightly  above  the  critical  point,  to 
obtain  the  benefit  of  all  three  results  mentioned  above.  As  there 
is  such  a  difference  in  the  methods  (and  results)  covered  by  ^  the 
simple  term  annealing,  it  is  customary  to  indicate  more  definitely 
what  kind  is  intended:  ordinary  or  commercial  annealing  is  a 
term  somewhat  loosely  used  to  mean  reheating  to  some  tern- 


23  2  HEAT  TREATMENT 

perature  either  slightly  below  or  above  the  critical  range  followed 
by  slow  cooling  either  in  air  or  otherwise  according  to  the  size  of 
the  object;  where  the  material  is  to  be  rendered  soft  the  terms 
soft  annealing,  dead  annealing  or  dead  soft  annealing  are  used; 
the  method  of  cooling  may  also  be  indicated,  as  air  cooling, 
furnace  cooling  or  annealing,  lime  cooling  or  annealing,  etc. 
Where  a  substance  such  as  lime  or  ashes  is  employed,  the  heated 
article  is  buried  in  it  and  allowed  to  remain  until  cold  or  nearly 
so;  the  same  with  furnace  annealing.  A  form  of  annealing  known 
as  normalizing  consists  in  reheating  to  a  temperature  above  the 
critical  range,  holding  at  that  temperature  a  certain  length  of 
time,  and  then  cooling  in  air:  it  is  commonly  used  to  secure  uni- 
form conditions  on  material  treated  in  various  ways  or  where,  as 
in  the  case  of  billets,  the  finishing  temperature  and  amount  of 
hot  working  have  resulted  in  a  very  coarse  grain;  this  term  was  sug- 
gested by  Arnold,  and  equalizing  was  suggested  by  Stead  as  more 
suitable  but  has  not  come  into  any  extended  employment.  Flash 
annealing  or  skin  annealing  is  the  name  sometimes  given  to  a 
rapid  heating  operation  designed  to  soften  only  the  outer  portion 
or  skin.  Fine  material,  such  as  wire  or  thin  sheets,  is  usually  pro- 
tected from  the  oxidation  which  would  result  if  heated  directly  in 
the  air,  by  enclosing  in  a  suitable  metal  box  or  pot:  this  is  called 
close  annealing,  box  annealing,  or  pot  annealing.  The  Jones 
process  consists  in  annealing  in  boxes  or  retorts  in  which  a  non- 
oxidizing  gas  is  maintained.  In  William  Smith's  process  for 
annealing  wire  before  finishing,  the  heating  was  conducted  in  a 
furnace  in  which  a  wall  prevented  the  flame  from  striking  the  wire. 
This  was  subsequently  taken  out  and  allowed  to  cool  in  oxide  of 
manganese,  after  which  the  drawing  was  completed. 

Combined  quenching  and  reheating  operations  are  employed  to 
add  to  the  advantage  of  annealing  in  securing  high  ductility  with 
almost  complete  absence  of  internal  strains,  those  accruing  from 
quenching  consisting  in  smaller  grain  and  finer  condition  of  pearl- 
ite.  These  consist  essentially  of  a  quenching  operation,  the  same 
as  for  hardening,  but  not  necessarily  so  vigorous,  followed  by  a 
reheating  above  what  is  employed  for  tempering  as  described 
above.  The  first  step  (quenching)  is  sometimes  designated  as 
grain  refining  treatment,  and  the  second  as  tempering,  although 
toughening,  drawing  back,  drawing,  or  reheating — particularly 
toughening — are  preferable  to  avoid  confusion.  The  entire 
operation  is  also  commonly  referred  to  as  toughening,  and  to  indi- 
cate the  quenching  medium,  the  terms  air  toughening,  water 
toughening,  or  oil  toughening  are  used  (unfortunately  these  last 
three  terms  are  also  used  to  indicate  where  hardened  material  is 
tempered  to  about  a  yellow  temper  color  and  then  cooled  in  the 
give  medium) .  Annealing  is  also  used  in  the  same  sense.  Tough 
hardening  was  the  name  suggested  by  Brinell  for  this  treatment 
as  applied  to  mild  steel.  Double  annealing  was  first  suggested 
by  Wallerant  (Wallerant's  process)  and  consists  of  quenching  in 
water,  oil,  or  other  suitable  medium  from  above  the  upper  critical 
point,  followed  by  reheating  to  about  500  to  650°  C.  (930  to 
1200°  F.).  Negative  hardening  (Osmond)  is  somewhat  similar: 


HEAT  TREATMENT— HEATER        233 

soft  steel,  if  brittle,  particularly  from  heating  which  has  been  too 
long  or  at  too  high  a  temperature,  is  rendered  much  more  tough 
and  ductile  by  heating  to  about  800°  C.  (1470°  F.)  and  plunging 
it  into  boiling  water,  no  hardening  ensuing.  This  term  (and 
negative  quenching)  is  also  used  where  the  object  is  so  large  or 
the  medium  so  slow  in  its  action  (e.g.,  hot  water,  oil  or  molten 
lead)  that  hardening  in  any  degree  does  not  result  (see  special 
hardening  processes).  The  Terre-Noire  process  for  tempering 
hoops,  etc.,  consisted  in  (a)  heating  to  a  yellow  (temper  color) 
heat,  and  plunging  into  oil:  (b)  reheating  to  a  bright  or  a  dull 
cherry  red  and  plunging  again  into  oil.  Various  processes  have 
been  devised  for  accelerating  the  rate  of  cooling  through  the 
critical  range.  TschernofFs  process  consisted  in  cooling  rapidly 
until  black,  for  small  objects  in  air,  for  larger  objects  oil  or  water 
depending  upon  the  size,  then  finishing  slowly  so  that  during  the 
second  stage  the  hardening  would  be  undone  and  the  severe 
strains  removed.  In  the  Coffin  axle  process  the  axle  is  allowed  to 
cool  at  the  ordinary  rate  and  is  then  jeheated  to  just  above  the 
upper  critical  point,  quenched  in  oil  until  its  temperature  is  at  the 
lower  critical  point,  and  then  cooled  in  air.  This  treatment, 
besides  refining  the  grain,  also  renders  the  axle  very  much 
tougher.  In  one  experiment  it  was  shown  that  the  elastic  limit 
had  been  increased  by  this  method  over  46%,  the  tensile  strength, 
elongation,  and  reduction  of  area  remaining  nearly  constant. 
Coffin's  rail  process  consists  in  immersing  the  rail  in  water, 
immediately  after  leaving  the  rolls,  until  its  temperature  has  fal- 
len to  the  lower  critical  point,  submerged  jets  of  water  playing 
upon  the  thick  head  to  equalize  the  rate  of  cooling.  It  is  then 
allowed  to  cool  slowly  in  the  air.  Sandberg's  process  for  rails  is 
very  similar  to  Coffin's  rail  process,  cold  air  being  blown  on  the 
head,  after  leaving  the  rolls.  The  Kennedy-Morrison  process 
was  devised  for  the  purpose  of  giving  rails  a  finer  structure,  and 
consisted  in  holding  them  on  the  tables  a  short  time  before  the 
last  pass  to  give  them  a  lower  finishing  temperature.  But  as  the 
reduction  in  the  last  pass  is  very  slight,  the  effect  obtained  is  also 
slight.  Garnaut  and  Siegfield's  process  for  hardening  and  refin- 
ing bars  appears  to  be  deserving  of  very  little  consideration.  It 
depends  upon  (a)  forging  a  heated  bar  covered  first  with  common 
salt,  and  afterward  with  a  miscellaneous  mixture,  (b)  reheating 
and  rehammering,  and  (c)  reheating  and  quenching  in  an  aqueous 
solution  of  various  substances. 

In  commercial  work  the  furnace  charge  for  annealing  is  called 
the  annealing  charge;  for  quenching,  the  quenching  charge; 
and  for  drawing  back  or  toughening  after  quenching,  the  temper- 
ing charge  (sometimes  also  annealing  charge). 

Heat  Treatment  Crack. — See  page  222. 

Heat  Treatment,  Effect  of  on  Density. — See  pages  224  and  448. 

Heat  Unit. — See  page  199. 

Heat  of  Vaporization. — See  page  202. 

Heat  Weight.— See  page  201. 

Heater. — (i)  The  man  in  charge  of  a  heating  furnace;  (2)  a  piece  of 
preheated  iron  laid  upon  an  object  at  the  part  where  it  is  to  be 


234  HEATH  PROCESS— HEYN'S  REAGENTS 

bent  when  it  cannot  be  heated  in  a  furnace  direct;  it  is  also  used 

for  skin-drying  molds  (Eng.). 
Heath  Process. — See  page  113. 
Heathfield  Process. — See  page  371. 
Heating  Coke. — See  page  97. 
Heating  Crack. — See  Crack. 
Heating  Curve. — See  Curve. 
Heating  Curve  Method. — Of  determining  critical  points:  see  page 

265. 

Heating  Furnace. — See  page  184. 
Heating  Furnace  Cinder. — See  Slag. 
Heating  Methods  of  Etching.— See  pages  286  and  288. 
Heaton  Process. — See  page  386. 
Heavy  Alloy. — See  Alloy. 
Heavy  Metal.— See  Alloy. 
Heberlein  Pot.— See  page  44. 
Heerzeel  and  Paulis  Process.— See  page  386. 
Helfenstein  Furnace.— See  page  158. 
Helsby  Method.— See  page  503. 
Helve.— See  Hammer. 

Hematite. — (i)  Iron  ore:  see  page  243;  (2)  pig  iron:  see  page  344 
Hemicrystalline  Crystal. — See  page  122. 
Hemihedron. — See  page  122. 
Hemimetamorphosis. — See  page   122. 
Hemipelic  Structure. — See  page  125. 
Hemiprismatic  System. — Of  crystallization:  see  page  120. 
Hemitrope. — See  page  124. 

Hen  and  Chickens  Method. — Of  Casting:  see  page  6r. 
Henderson  Process. — See  page  386. 
Henning's  Spectral  Pyrometer. — See  page  208. 
Heraus  Furnace. — See  page  158. 
Bering  Furnace.— See  page  158. 
Heroult  Furnace. — See  page  159. 
Hess's  Law. — See  page  200. 
Heterocellular  Structure. — See  page  126. 
Heterochrome  Photometer,  Nordman's. — See  page  208. 
Heterogeneous;  Heterogeneity. — Not  of  the  same  composition 

throughout;  not  uniform. 

Heterogeneous  Distribution  of  Carbon. — See  page  2T3. 
Heterogeneous  Equilibrium. — See  page  328. 
Heterogeneous  Steels. — See  Homogeneous  Steels. 
Heterogeneous  System. — See  page  327. 
Heteromorphic. — See  page  122. 
Heterotomous. — See  page  124. 
Heussler  Alloys.— See  Alloy. 
Hewitt  Process. — See  page  380. 
Hexad. — See  page  86. 

Hexagonal  System.— Of  crystallization:  see  page  120. 
Hexahedrite. — See  page  292. 
Hexavalent. — See  page  86. 

Heyn  and  Baux's  Method. — For  sulphur  prints:  see  page  288. 
Heyn's  Reagents. — For  etching:  see  page  287. 


HIBBARD  METHOD— HOLOAXIAL  235 

Hibbard  Method. — For  fluid  compression:  see  page  63. 

High  Bloomary. — See  page  142. 

High  Boil.— See  page  376. 

High  Carbon  Steel. — See  page  455. 

High  Furnace  (rare). — Blast  Furnace. 

High  Gage.— See  page  186. 

High  Grade. — Sometimes  used  for  high  carbon. 

High  Grade  Fireclays. — See  page  396. 

High  Heat  Tools.— See  page  446. 

High  Heat  Treatment. — In  Taylor- White  process:  see  page  446. 

High  Phosphorus  Steel. — Steel  containing  a  considerable  percent- 
age of  phosphorus,  or  more  than  is  permitted  by  the  given  speci- 
fication. 

High  Pressure  Combustion. — Using  forced  draft. 

High  Range  Mercury  Thermometer. — See  page  205. 

High  Resistance  Steel. — See  page  443. 

High  Silicon  Iron;  Pig. — See  pages  344  and  354. 

High  Silicon.  Softener. — See  page  347. 

High  Speed  Steel ;  Tool  Steel.— See  page  446. 

High  Sulphur  Steel. — Steel  containing  a  considerable  percentage  of 
sulphur,  or  more  than  is  permitted  by  the  given  specification. 

High  Temper  Steel.— See  Temper. 

High  Tension  Steels. — See  page  443. 

Hilgenstock  Process.— See  page  386. 

Hilpert  and  Colver-Glauert's  Reagent. — For  etching:  see  page  287. 

Hinsdale  Process. — (i)  For  casting:  see  page  62:  (2)  for  fluid 
compression:  see  page  63. 

Hiorth  Furnace.— See  page  160. 

Hobson  Pyrometer. — See  page  209. 

Hoerde  Process.— See  page  386. 

Hofer  Process. — See  page  141. 

Hoist.— See  page  33. 

Holborn  Gas  Pyrometer. — See  page  207. 

Holborn-Kurlbaum  Optical  Pyrometer. — See  page  207. 

Holborn  and  Wien  Pyrometer. — See  page  208. 

Hold  the  Heat.— See  page  314. 

Hole. — (i)  Of  a  crucible  furnace:  see  page  114 ;  (2)  in  wire  drawing: 
see  page  507. 

Hole  Furnace.— See  page  114. 

Holland  Process. — See  page  73. 

Holley  Movable  (Removable)  Bottom.— See  page  17. 

Hollow. — Of  steel,  seamy  or  laminated. 

Hollow  Fire.— See  page  79. 

Hollow  Forging.— See  Forging. 

Hollow  Pressed  Axle. — See  Mercader  Hollow  Pressed  Axle. 

Hollow  Roll.— See  page  404. 

Holloway  Process. — A  method  for  reducing  metallic  sulphides  by 
blowing  air  through  them  whole  molten  (Bessermerizing),  the 
sulphur  acting  as  the  fuel  to  supply  the  necessary  heat;  not  a 
success  for  sulphides  of  iron. 

Holo-  (prefix). — See  page  122. 

Holoaxial.— See  page  122. 


236  HOLOCRYSTALLINE— HOT  BLAST  PYROMETER 

Holocrystalline. — See  page  122. 

Holohedral. — See  page  122. 

Holoisometric. — See  page  122. 

Holosiderite. — See  page  291. 

Holosymmetric. — See  page  122. 

Holsters. — See  page  403. 

Homocellular  Structure. — See  page  126. 

Homoeomorphism. — See  page  121. 

Homogeneity  Test. — See  page  476. 

Homogeneous  Distribution  of  Carbon. — See  page  213. 

Homogeneous  Equilibrium. — See  page  328. 

Homogeneous  Metal  (obs.). — A  name  formerly  applied  to  crucible 
or  other  steel,  made  in  a  molten  condition,  in  contradistinction 
to  the  heterogeneous  condition  of  blister  steel.  -'y; 

Homogeneous  Nickel  Steel  Armor  Plate. — See  page  8. 

Homogeneous  Steel  (obs.). — (i)  Used  occasionally  to  distinguish 
from  casehardened  or  cemented  steels;  of  same  composition  (par- 
ticularly carbon)  throughout;  in  this  connection  casehardened 
or  cemented  steels  might  be  termed  heterogeneous  steels;  (2) 
free  from  blowholes,  solid;  (3)  a  variety  of  crucible  steel  easily 
bent  and  worked. 

Homogeneous  System. — See  page  328. 

Homogenize. — See  page  328. 

Homohedral. — See  page  122. 

Honeycombed. — See  page  55. 

Hooke's  Law.— See  page  334. 

Hooked  Fracture.— See  page  178. 

Hoop.— See  Coil. 

Hoop  Mill. — See  page  415. 

Hopper. — A  door  or  trap  at  the  bottom  of  a  chute  or  shaft  by 
means  of  which  the  contents  can  be  dumped  out  or  their  descent 
regulated:  see  also  page  32. 

Horizontal  Heating  Furnace. — See  page  184. 

Horizontal  Regenerators. — See  page  312. 

Horizontal  Testing  Machine. — See  page  469. 

Horn. — See  page  430. 

Horse.— See  Salamander. 

Horseshoe  Iron. — See  page  378. 

Horsfall  Process.— See  page  231. 

Hot. — (i)  Of  pig  iron  in  the  molten  or  fluid  condition;  molten  metal; 
(2)  of  steel  when  it  is  hot  enough  for  rolling  or  forging,  or  when  it 
is  finished  at  a  high  temperature;  (3)  of  working,  when  metal  is 
heated,  in  contradistinction  to  cold  working. 

Hot  Bed.— See  page  414. 

Hot  Bend  Test— See  page  476. 

Hot  Blast.— See  Blast. 

Hot  Blast  Charcoal  Iron. — See  page  343. 

Hot  Blast  Cupola.— See  page  182. 

Hot  Blast  Furnace. — See  page  39. 

Hot  Blast  Iron;  Pig.' — Pig  iron  smelted  with  hot  blast. 

Hot  Blastman. — See  page  38. 

Hot  Blast  Pyrometer. — See  page  210. 


HOT  BLOW— HYDRAULIC  FORGING  237 

Hot  Blow. — See  page  20. 

Hot  Blowing  Iron;  Metal;  Pig. — See  page  20. 

Hot  Crack.— See  Crack. 

Hot  Drawn. — Of  tubes :  see  page  491. 

Hot  Ductility. — See  page  331. 

Hot  Etching.— See  page  286. 

Hot  Flame  Weld. — See  page  503. 

Hot  Forging. — Used  only  in  contradistinction  to  cold  working. 

Hot  Galvanizing. — See  page  370. 

Hot  Hanging. — Of  a  blast  furnace:  see  page  35. 

Hot  Iron. — See  pages  20  and  343. 

Hot  Jacket. — See  page  36. 

Hot  Junction. — Of  a  thermocouple:  see  page  209. 

Hot  Melting. — See  page  376. 

Hot  Metal. — Pig  iron  from  the  blast  furnace  before  it  has  solidified; 
also  called  direct  metal,  more  particularly  in  the  sense  that  it  is 
to  be  used  in  this  condition  in  some  refining  process. 

Hot  Punching. — See  Forging. 

Hot  Rolling. — Used  only  in  contradistinction  to  cold  working. 

Hot  Saw. — A  circular  power  saw  for  cutting  hot  steel. 

Hot  Scaffold.— See  page  35. 

Hot  Scale. — A  scale  for  weighing  material  while  hot. 

Hot  Short;  Shortness.— See  Brittleness. 

Hot  Spot. — See  pages  36  and  58. 

Hot  Stable  State.— See  page  327. 

Hot-top  Sinkhead. — See  page  56. 

Hot  Water  Hardening. — See  page  229. 

Hot  Working. — Working  metal  after  heating  it  to  a  suitable  tem- 
perature, in  contradistinction  to  working  it  cold. 

Housing;  Housing  Cup;  Pin;  Screw. — See  page  403. 

Howe's  Formulae. — For  elongation:  see  page  338. 

Howell  Mill. — See  page  434. 

Hudson  (J.  J.)  Process. — See  page  77. 

Hughes  (Wm.  B.)  Process.— See  page  318. 

Humbert  Process. — See  page  159. 

Humfrey's  Amorphous  Iron  Theory. — Of  hardening:  see  page  281. 

Humid  Analysis;  Process. — See  page  82. 

Hunch  Pit.— See  page  316. 

Hungry. — Of  pig  iron  rich  in  silicon  and  phosphorus;  if  used  for 
puddling  it  requires  more  ore  or  oxides  for  their  oxidation  and 
removal. 

Hunt  Process. — See  page  380. 

Huntington-Heberlein  Pot  Process. — See  page  44. 

Huntsman  Process. — See  page  113. 

Huntsman  Steel  (obs.). — Crucible  steel,  after  the  inventor,  Benja- 
min Huntsman  (1746). 

Husgafvel's  High  Bloomary.— See  page  142. 

Huth  Process. — See  page  62. 

Hyaloid  (rare). — Glassy  or  transparent. 

Hdraesfer  Process. — See  page  369. 

Hydrate  Ore.— See  page  244. 

Hydraulic  Forging.— See  Forging. 


238  HYDRAULIC  PRESS— HYSTERESIS  GAP 

Hydraulic  Press. — See  Press. 

Hydraulic  Shears. — See  page  412. 

Hydrochloric  Acid.— For  etching:  see  page  287. 

Hydrogen.— H;  at.  wt.,  i;  melt,  pt.,  -257°  C.  (-431°  F.);  boil, 
pt,  —253°  C.  (—423°  F.);  sp.  gr.,  0.0695  (air  =  i);  i  liter  weighs 
0.089873  gram,  called  i  crith.  It  is  a  colorless,  odorless,  and 
tasteless  gas,  and  is  the  lightest  substance  known.  It  has  a 
powerful  affinity  for  oxygen  and,  in  combination  with  it,  occurs 
as  water.  It  is  absorbed  or  occluded  by  iron  to  a  considerable 
extent,  and  tends  to  make  the  metal  brittle. 

Hydrogen  Company's  Process. — See  page  370. 

Hydrogen  Point. — See  page  264. 

Hydrogen  Theory. — Of  passivity:  see  page  364. 

Hydrohematite. — See  page  244. 

Hydro-metallurgy. — Pyro-metallurgy,  q.v. 

Hydrometer. — An  instrument  for  measuring  the  specific  gravity  of 
liquids,  consisting  of  a  graduated  tube,  one  end  of  which  is  loaded 
so  the  tube  will  remain  upright. 

Hydro -Pyrometer. — See  page  207. 

Hydrosiderum  (obs.). — Or  wassereisen;  names  suggested  by  Mayer 
(1782)  for  phosphide  of  iron  which  he  discovered  in  pig  made  from 
bog  ore,  and  which,  at  the  time,  he  thought  was  a  new  metal. 

Hydrothermal  Fusion. — See  page  201. 

Hygrometer. — An  instrument  for  measuring  the  percentage  of 
moisture  in  gases,  more  particularly  air;  there  are  various  types. 

Hygrometric  Moisture ;  Water. — See  Water. 

Hygroscopic. — Having  an  affinity  for  moisture. 

Hygroscopic  Moisture. — See  Water. 

Hyper-  (prefix). — In  chemistry:  see  page  88. 

Hyper-aeolic  Steel. — See  page  273. 

Hyper-eutectic  Cast  Iron. — See  page  271. 

Hyper-eutectic  Steel. — See  page  271. 

Hyper-eutectoid  Steel.— See  page  273. 

Hypertectic. — See  page  269. 

Hypertectic  Point. — See  page  269. 

Hypo-  (prefix). — In  chemistry:  see  page  88. 

Hypo-aeolic  Steel. — See  page  273. 

Hypo-eutectic  Alloys. — See  page  271. 

Hypo-eutectic  Cast  Iron. — See  page  271. 

Hypo-eutectic  Steel.— See  page  271. 

Hypo-eutectoid  Steel. — See  page  271. 

Hysteresis.— Retardation  of  magnetization  (magnetic  hysteresis). 
The  persistency  with  which  certain  bodies  tend  to  retain  their 
previous  condition.  Professor  Ewing  uses  the  word  in  a  more 
general  sense  of  a  dissipation  of  energy  occurring  in  any  cycle  of 
operations  (I.  A.  T.  M.),  see  pages  269  and  327,^ 

Hysteresis  Gap;  Temperature,— See  page  265, 


'.. — Chemical  symbol  for  iodine:  see  page  84. 

ii. — Chemical  symbol  for  indium:  see  page  84. 

r. — Chemical  symbol  for  indium :  see  page  84. 

!.  A.  T.  M. — International  Association  for  Testing  Materials. 

!.  A.  T.  M.  Iron-Carbon  Diagram. — See  page  271. 

!.  D. — Inside  diameter. 

[.  E.  E. — Institute  of  Electrical  Engineers  (Eng.). 

-ic  (suffix), — In  chemistry:  see  page  88. 

•ide  (suffix). — In  chemistry:  see  page  88. 

ideal  Gas.— See  Gas. 

idiomorphic  Crystal. — See  page  122. 
Idle  Roller;  Idler.— See  page  407. 
Igewsky's  Reagent. — For  etching:  see  page  287. 
Igneous  Fusion. — See  page  201. 
Ignition;  Ignition  Point. — See  page  202. 
Illingworth  Method. — See  page  63. 
Illumination;  Illuminator. — See  page  285. 
Ilmenite. — See  page  245. 
Image. — See  page  285. 
Imbricated  Structure.— See  page  126. 
Immiscible. — Incapable  of  mixing. 

Impact. — (i)  General:  see  page  333 r  (2)  coefficient  of:  see  page  481. 
Impact  Crushing  Tests.— See  page  481. 
Impact  Energy.— See  page  481. 
Impact  Shear  Test. — See  page  482. 
Impact  Stress. — See  page  333. 
Impact  Test. — See  page  481. 
Imperatori  Process. — See  page  142. 
Imperfect  Cleavage. — See  page  124. 
Imperfect  Elasticity. — See  page  330. 
Imperfection. — Defect. 
Imperial  Wire  Gage.— See  page  188. 

Impregnation. — The  absorption  or  combination  of  one  substance 
with  another,  e.g.,  the  impregnation  of  iron  with  carbon;  some- 
times used  in  the  sense  of  absorbing  all  possible. 
Impregnation  Zone. — See  page  293. 
Improved  Wire. — See  page  509. 

Impurity. — A  substance  contaminating,  or  detracting  from  the 
purity  of,  another  substance.  It  is  a  mechanical  or  a  chemical 
impurity  depending  upon  whether  it  is  simply  intermixed  or  is 
chemically  combined. 

In  Blast. — Of  a  blast  furnace:  see  page  37, 
Inactive  Iron. — See  page  364. 
Incandescent. — Glowing  with  intense  brilliance,  e.g.,  incandescent 

carbon  is  carbon  at  a  white  heat. 
Incandescent  Welding.— See  page  503. 
Incipient  Combustion.— See  page  202. 

239 


240      INCIPIENT  FUSION— INTEGRAL  RADIATOR 

Incipient  Fusion,  Zone  of. — See  page  36. 

Inclusion. — Something  included  or  enclosed  in  a  substance,  such  as 
gas  or  mechanically  suspended  foreign  matter:  see  page  57. 

Incompatibility  Theory. — See  page  289. 

Incomplete  Combustion. — See  page  202. 

Incomplete  Crystal. — See  page  122. 

Incomplete  Equilibrium. — See  page  326. 

Incomplete  Heterogeneous  Equilibrium. — See  page  327. 

Incomplete  Purification. — Not  carried  to  its  greatest  possible  extent, 
as  in  pig  washing. 

Incongruent  Freezing. — See  page  267. 

Index. — Of  corrosion:  see  page  107. 

Indian  Steel.— See  Wootz. 

Indifferent  Equilibrium. — See  page  327. 

Indirect  Heating  Furnace. — See  page  181. 

Indirect  Processes;  Recovery  Processes. — In  the  manufacture  of 
coke:  see  page  96. 

Indirect  Resistance  Heating. — See  page  153. 

Indistinct  Cleavage. — See  page  124. 

Individual  Deviation. — Of  slipping:  see  page  283. 

Induction  Furnace;  Heating. — See  page  153. 

Indurate;  Induration. — To  harden;  hardening. 

Inequiaxed  Crystal;  Grain. — See  page  217. 

Inequilibrium. — See  page  326. 

Inert  Gas. — See  page  70. 

Influence  of  Time. — On  grain  size:  see  page  214. 

Infusion  Method  of  Hardening. — See  page  69. 

Infusorial  Earth. — See  page  396. 

Ingate. — See  page  299. 

Ingot.— See  page  53. 

Ingot  Crack. — A  crack  in  the  side  of  an  ingot  formed  during  cooling. 

Ingot  Iron. — (i)  The  term  formerly  suggested  for  iron  products  low 
in  carbon  produced  in  a  molten  condition;  still  employed  in  some 
foreign  countries  in  this  sense;  (2)  a  trade  name  for  open  hearth 
steel  low  in  carbon  and  impurities. 

Ingot  Metal. — (i)  Metal  cast  in  ingots;  (2)  ingot  iron. 

Ingot  Nickel. — See- page  353. 

Ingot  Steel  (rare). — Medium  or  high  carbon  steel  cast  in  ingots. 

Ingot  Tumbler.' — A  receptacle  mounted  on  a  buggy  to  convey  ingots 
from  the  soaking  pits  to  the  rolling  mill.  It  is  arranged  to  spill 
and  tip  the  ingot  out  when  it  reaches  the  roll  table. 

Ingotism. — See  page  57. 

Initial  Stress. — See  page  333. 

Inoculation. — See  page  268. 

Inorganic  Chemistry. — See  page  82. 

Inoxidizing  Coating;  Process. — See  page  362. 

Inset  Sprue. — See  page  299. 

Inside  Gage. — See  page  186. 

Insuluminum. — See  page  372. 

Intake. — (i)  The  place  where  the  gas  enters  a  furnace;  (2)  in  hy- 
draulic wqrk,  where  water  enters  a  construction. 

Integral  Radiator. — See  page  267. 


INTENSITY  OF  STRESS— I ONID  241 

Intensity  of  Stress.— See  page  333. 

Intercrystalline  Rupture. — See  page  123. 

Intergranular  Cement. — See  page  281 . 

Intergranular  Deformation;  Flow. — See  page  281. 

Intergranular  Fracture. — See  page  178. 

Intergranular  Motion. — See  page  282. 

Interior  Shrinkage. — See  page  54. 

Intel-metallic  Alloy;  Compound. — See  Alloy. 

Intermittent  Brittleness. — See  Brittleness. 

Internal  Crack.— See  Crack. 

Internal  Crystal. — See  page  127. 

Internal  Defect. — See  page  333. 

Internal  Fissure. — See  Crack. 

Internal  Force. — See  page  332. 

Internal  Fracture. — See  pages  179  and  333. 

Internal  Friction. — See  page  267. 

Internal  Orientation. — See  page  127. 

Internal  Rupture. — See  pages  333  and  491. 

Internal  Strain;  Stress. — See  pages  281  and  332. 

Internal  Surface  of  Weakness. — See  page  283. 

Internal  Tension. — See  page  281. 

Internally  Blown  Converter. — See  page  19. 

Interpenetration. — A  general  term  for  those  actions  by  which  one 

portion  of  matter  is  distributed  either  wholly  or  in  part  through  a 

space  containing  matter  generally  of  a  different  kind  (I.  A.  T.  M.) : 

see  page  124. 

Interpolation. — See  Curve. 
Interrupted  Cleavage. — See  page  124. 
Interstrain;  Interstrain  Theory. — In  connection  with  hardening: 

see  page  281. 

Interstratal  Movement. — See  page  282. 
Intimate  Mixture. — See  page  83. 
Intra-crystalline  Fracture. — See  page  1 78. 
Intra-crystalline  Rupture. — See  page  123. 
Intra -granular  Flow. — See  page  281. 
Latra-pearlitic  Flow. — See  page  281. 

Intrusion. — Material  forced  into  a  cavity  from  the  surrounding  wall. 
Intumescence. — Particularly  of  certain  crystals  on  heating;  swelling 

up. 

Invar. — See  page  451. 
Invariant  System. — See  page  327. 
Inverse  Ratio. — In  testing:  see  page  475. 
Inversion. — See  page  271. 

Inversion  Temperature. — See  pages  108  and  327. 
Inverted  Molds. — See  page  59. 
Invisible. — A  name  given  by  H.  M.  Howe  to  the  condition  when  the 

interior  of  a  furnace  or  crucible  and  the  bodies  contained  in  it  are 

at  the  same  temperature,  and  the  bodies  are  therefore  invisible. 
Inwall. — See  page  32. 

Iodine. — One  of  Osmond's  reagents:  see  page  287. 
Ion;  Ionic  Dissociation;  Theory. — See  page  89. 
lonid. — See  page  89. 

16 


242  IRELAND  PROCESS— IRON  OCHRE 

Ireland  Process. — See  page  142. 
Irestone. — See  page  243. 
Iridescent  Ore. — See  page  244. 

Irish  Temper. — See  Temper. 
Iron. — Pig  iron,  q.v. 

Iron.— Fe;  at.  wt.,  56;  melt,  pt,  1505°  C.  (2741°  F.);  sp.gr.,  7.84 
to  8.139.  It  is  rarely  found  in  the  metallic  condition  in  nature 
except  as  meteorites  (q.v.);  its  chief  occurrence  is  in  combination 
with  oxygen  (see  Iron  Ore).  The  pure  metal  has  a  white  lus- 
trous appearance,  does  not  harden  appreciably  on  quenching, 
and  is  strongly  attracted  by  a  magnet,  although  it  cannot  itself  be 
made  magnetic  except  when  containing  carbon,  or  while  an  elec- 
tric current  is  passed  around  it.  The  pure  metal  is  merely  a 
metallurgical  curiosity.  Nearly  pure  iron  is  now  regularly  pro- 
duced electrolytically  (see  Electrolytic  Iron).  In  certain  cases 
combinations  of  iron  and  oxygen  act  as  an  acid  to  form  salts. 
The  'derivatives  of  the  hypothetical  ferrous  acid,  H2Fe2O4,  are 
termed  ferrites,  e.g.,  ZnFe2O4,  zinc  ferrite;  another  hypothetical 
acid,  ferric  acid  (H2FeO4)  forms  salts  known  as  ferrates.  For 
producing  pure  iron  Peligot's  method  was  to  reduce  heated  fer- 
rous chloride  with  hydrogen,  while  in  PommarSde's  method  zinc 
was  substituted  for  hydrogen. 

Irons. — See  page  291. 

Iron  of  Bessemer. — Name  suggested  for  iron  or  low  carbon  steel 
made  by  the  Bessemer  (pneumatic)  process. 

Iron  Blast  Furnace  (rare). — Used  only  to  distinguish  it  from  a  cop- 
per or  a  lead  blast  furnace. 

Iron  Blower. — See  page  492. 

Iron  Cancer. — See  page  106. 

Iron-Carbide  Solution. — In  hardening:  see  page  281. 

Iron-Carbon  Diagrams;  System. — See  page  271. 

Iron  Carbonyl. — See  Carbon. 

Iron-Cementite  Diagram. — See  page  271. 

Iron  Change. — An  allotropic  change  occurring  in  the  condition  of 
iron. 

Iron  Company's  Process. — See  page  138. 

Iron  Glance. — See  page  243. 

Iron  Glass. — See  page  292. 

Iron-Graphite  Diagram. — See  page  271. 

Iron  Hardenite. — See  page  275. 

Iron  Hat. — See  page  245. 

Iron-Iron  Hydroxide  Eutectic. — See  page  265. 

Iron  Ladle. — See  Ladle. 

Iron  Man  (Eng.). — A  name  given  by  workmen  to  certain  mechan- 
ical devices  which  replace  hand  labor,  such  as  charging  machines 
or  mechanical  puddlers:  see  page  379. 

Iron  Meteorite. — See  page  291. 

Iron  Mine. — See  page  243. 

Iron  Mold. — See  page  296. 

Iron  Nitride. — See  page  279. 

Iron  Notch. — See  page  32. 

IronOchre. — See  page  244. 


IRON  ORE  243 

Iron  Ore.— See  also  Ore.  Rarely  called  (Eng.)  ironstone,  iron 
mine,  or  irestone.  Iron  ores,  as  a  rule,  contain  from  25  to  70  % 
of  iron;  if  less  than  40%  they  must  first  be  concentrated  (part  of 
the  gangue  removed),  and  if  less  than  25%  they  cannot  be  con- 
sidered commercially,  as  the  cost  of  smelting  is  too  great.  Concen- 
tration may  consist  in  washing,  i.e.,  employing  water  to  effect  a 
separation  according  to  the  relative  specific  gravities,  or,  in  the  case 
of  magnetic  ores,  by  some  form  of  magnetic  separation,  the  iron 
being  attracted  by  a  magnet  while  the  gangue  is  unaffected;  in 
both  cases  the  ore  must  be  in  a  moderately  fine  condition.  In 
the  case  of  carbonates,  or  ores  containing  carbonaceous  matter, 
roasting  is  resorted  to.  At  the  present  time  in  this  country  the 
ores  as  mined  average  slightly  over  50%,  the  Lake  ores  running 
higher  than  those  in  the  South,  sometimes  over  60%.  In  con- 
sidering the  iron  minerals  a  division  is  made  according  to  whether 
or  not  they  are  available  for  the  iron  industry.  Iron  ores  may 
be  classified  as  follows : 

I.  Chemical  composition : 

1.  Oxide. 

2.  Carbonate. 

3.  Arsenide. 

4.  Chromate. 

5.  Phosphate. 

6.  Sulphide. 
6.  Titanate. 

8.  Tungstate. 

II.  Phosphorus  content  (practically  all  the  phosphorus  is 
reduced  in  making  pig  iron):  will  yield  pig  containing: 

9.  Not  over  0.1%  of  phosphorus:  Bessemer  ore,  acid 
Bessemer  ore  (rare),  hematite  (Eng.). 

10.  Over  o.i  %  of  phosphorus:  non-Bessemer  ore,  basic 
Bessemer  ore  (foreign);  cold  short  ore  (Eng.). , 

III.  Nature  of  the  gangue : 

11.  Silicious  ore:  high  silica. 

12.  Dry  ore  (Eng.):  low  silica. 

13.  Calcareous  ore:  nigh  lime  and  bases. 

14.  Red  short  ore :  high  sulphur. 

15.  Self- fluxing  ore:  where  the  proportion  of  lime,  mag- 
nesia, alumina,  and  silica  are  such  that  no  addition  (or 
very  little)  of  flux  is  needed  for  smelting. 

1 6.  Self-roasting    ore:  where    sufficient    carbonaceous 
matter  is  present  for  roasting  without  the  necessity 
for  extraneous  fuel. 

Commercial  ores : 

Oxides. — (i)  Anhydrous  ferric  oxide,  Fe2O3,  containing  when 
pure  70%  Fe.  ^  In  color  it  varies  from  a  brilliant  black  to  a  brick 
red.  It  is  ordinarily  known  as  hematite,  haematite  (Eng.),  red 
hematite,  or  red  iron  ore;  more  rarely  as  red  iron  mine  (Eng.), 
red  mine  stone  (Eng.),  bloodstone,  or  red  slag  ironstone  (Eng.). 
On  account  of  certain  characteristics  the  following  names  are 
sometimes  used:  specular  iron  ore  or  iron  glance,  when  black  and 


244  IRON  ORE 

lustrous;  iridescent  ore,  also  lustrous,  but  having  peacock  colors, 
and  may  be  hematite  or  limonite;  micaceous  hematite,  or  mica- 
ceous iron  ore,  a  pure  form,  usually  gray  in  color,  and  having  a 
scaly  structure;  oolitic  ore,  having  the  appearance  of  fish  eggs, 
consisting  of  particles  of  sand  or  limestone  covered  with  ferric 
oxide,  either  anhydrous  or  hydrated;  pisolitic  ore,  where  the  par- 
ticles are  of  slightly  larger  size;  fossil  ore,  fossiliferous  red  hema- 
tite, or  red  fossil  ore,  often  self-fluxing;  kidney  ore  or  reniform 
iron  ore,  having  the  shape  of  kidneys;  frondescent  hematite,  hav- 
ing a  radiating  structure;  martite,  pseudomorphous  after  mag- 
netite; rubble  ironstone,  having  a  conglomerate  structure. 

Oxides.— (2)  Hydrated  ferric  oxide,  Fe2O3-nH2O  (the  various 
names  employed  do  not  always  indicate  a  definite  percentage  of 
water).  They  vary  in  color  from  a  light  yellow  to  a  dark  black- 
ish brown,  and  may  be  soft  and  pulverulent  or  hard  and  compact : 
Limonite,  goethite,  brown  hematite,  brown  iron  ore,  bog  ore, 
bog  iron  ore  or  lake  iron  ore  (Sweden);  turgite  or  hydrohematite 
is  a  variety  usually  classed  as  limonite.  On  account  of  their 
shape,  varieties  are  sometimes  called  bean  ore,  pipe  ore,  or 
milk'olithic  ore  (granulated). 

Oxides.— (3)  Magnetic  oxide,  Fe3O4  (FeO,  Fe2Oi),  contain- 
ing when  pure  72.4%  Fe;  a  black  hard  mineral  occurring  in 
large  masses  or  granulated,  and  strongly  attracted  by  a  magnet: 
magnetite,  magnetic  iron  ore,  lodestone,  black  iron  sand,  iron 
sand,  or  ologist  ore. 

Carbonates. — FeCO3,  when  pure  containing  48.3%  Fe, 
usually  roasted  to  drive  off  the  carbonic  acid,  when  a  mixture  of 
.  ferrous  and  ferric  oxides  results;  occurs  usually  in  granular 
masses  of  a  gray  or  brown  color;  commonly  called  siderite, 
spathic  ore,  spathic  iron  ore;  rarely  sparry  ore,  sperry  ore, 
spathic  carbonate,  chalybite,  sphaerosiderite,  brown  ore,  or 
white  ironstone;  on  account  of  certain  characteristics  the  fol- 
lowing names  have  been  applied:  black  band  (Eng.)  or  pottery 
mine  (North  Staffordshire),  contains  coal  and  occasionally 
some  limestone;  argillaceous  siderite,  argillaceous  iron  ore,  clay 
band  (Eng.),  clay  band  ironstone  (Eng.),  or  clay  ironstone  (Eng.), 
contains  considerable  amounts  of  clay. 

Minerals  which  have  little,  if  any,  application  as  a  source  of 
iron: 

Arsenide. — Leucopyrite  or  lollingite  is  an  arsenide  of  varying 
composition,  sometimes  containing  nickel,  etc.;  scorodite  is  a 
combination  of  ferric  oxide,  arsenic  oxide,  and  water. 

Chromates. — Chromite,  chromic  iron,  or  chrome  iron  ore, 
FeO,  Cr2O3,  is  a  massive  black  mineral  resembling  magnetite;  it  is 
very  infusible  and  is  used  as  a  refractory  (q.v.) ;  it  is  the  principal 
source  of  chromium. 

Phosphates. — Vivianite  or  blue  iron  earth  is  a  ferric  phosphate. 

Oxides. — Franklinite,  dodecahedral  iron  ore,  or  mangano- 
magnesian  magnetite,  is  an  oxide  of  iron  in  combination  with 
zinc  (of  which  it  is  a  source)  and  manganese;  it  is  a  hard  black 
mineral  resembling  magnetite.  Ochre,  iron  ochre,  or  red  ochre 
are  oxides  occurring  in  an  earthy  pulverulent  condition,  and  are 


IRON  OXIDE—  IRREGULAR  CONTRACTION       245 

used  principally  as  paints.  Gossan,  Gozzan,  or  iron  hat  is  a 
hydrated  oxide  of  iron  forming  the  cap  of  deposits  of  copper 
pyrites  due  to  the  mineral  having  been  decomposed  (weathered) 
and  the  copper  leached  out.  Laterite  is  a  hydrated  oxide  of  iron 
occurring  in  India;  it  is  soft  when  cut,  becoming  hard  on  exposure, 
and  is  used  principally  for  making  bricks. 

Sulphides.  —  Iron  pyrites,  pyrite,  or  yellow  pyrites  has  the  for- 
mula FeS2;  when  burned  in  the  manufacture  of  sulphuric  acid  the 
residue,  consisting  of  ferric  oxide  containing  an  extremely  small 
percentage  of  phosphorus,  is  sometimes  used  in  the  production  of 
low  phosphorus  pig,  and  is  known  as  purple  ore  or  blue  billy. 
Marcasite  or  white  iron  pyrites  has  the  same  formula  as  pyrite, 
but  differs  in  crystalline  form.  Arsenopyrite  or  mispickel  has 
the  formula  FeAsS.  Pyrrhotite,  magnetic  pyrites,  or  mundic  is  a 
combination  of  various  sulphides  of  iron,  and  usually  contains 
nickel,  of  which  it  is  an  important  source.  Copper  pyrites  or 
chalcopyrite  is  a  sulphide  of  iron  and  copper,  used  as  an  ore  of 
copper.  Melanterite  or  copperas  is  crystallized  ferrous  sulphate, 


Titanates.  —  Ilmenite,  menaccpnite  or  titanic  iron  ore  is  com- 
posed of  oxides  of  iron  and  titanium;  it  is  used  to  a  limited  extent 
as  an  ore  of  iron. 

Tungstates.  —  Wolframite  is  a  tungstate  of  iron  and  manganese 
and  is  the  principal  ore  of  tungsten. 

Manganese  Ores.  —  The  dividing  line  between  manganiferous 
iron  ores  and  manganese  ores  was  formerly  taken  at  44%  Mn. 
Later,  ores  with  as  little  as  40%  Mn  have  been  termed  man- 
ganese ores,  and  those  below  this  figure,  manganiferous  ores. 
The  following  classification  was  proposed  in  "Memoirs  of  the 
Geological  Survey  of  India,"  1909,  and  is  applicable  to  all  ores 
containing  over  a  combined  total  for  manganese  and  iron  of  50%: 

Mn%  Fe% 

Manganese  Ores  ....................     40  to  63  o  to  10 

Ferruginous  Manganese  Ores  .........     25  to  50  10  to  30 

Manganiferous  Iron  Ores  ............       5  to  30  30  to  65 

Iron  Ores  ..........................       o  to  5  45  to  70 

Ores  of  Steel  was  an  old  name  applied  to  ores  considered 
especially  suited  for  the  manufacture  of  wrought  steel  (as  distin- 
guished from  wrought  iron). 

Iron  Oxide.  —  See  pages  279  and  396. 

Iron  Phosphide.  —  See  page  279. 

Iron-Phosphorus  Diagram.  —  See  page  272. 

Iron  Pyrites.  —  See  above. 

Iron  of  Reaumur.  —  Name  suggested  for  malleable  cast  iron. 

Iron  Sand.  —  (i)  Ore:  see  page  243;  (2)  in  molding:  see  page  296. 

Iron  Side.  —  Of  a  converter:  see  page  18. 

Iron  Silicate  ;  Silicide.  —  See  page  279. 

Ironstone  ;  Ironstone  Meteorite.  —  (i)  Ore:  see  page  243;  (2)  meteor- 
ite: see  page  291. 

Iron  Sulphide.  —  See  page  279. 

Irregular  Contraction.—  See  page  222. 


246  IRREGULAR  FRACTURE— IZOD  TEST 

Irregular  Fracture. — See  page  179. 

Irreversible  Alloy ;  Process ;  Transformation.— See  pages  265  and 

327- 

Irritant. — A  term  proposed  by  Dumas  to  describe  the  action  of  spe- 
cial elements  present  in  iron  alloys,  chiefly  the  metals  nickel, 
manganese,  chromium,  and  tungsten,  though  silicon,  a  non-metal, 
could  be  added — namely,  that  they  were  irritants  to  the  non- 
metal  carbon.  These  metals  were,  generally  speaking,  not  power- 
ful in  themselves,  but  only  when  carbon  was  present. 

Irving  Furnace ;  Process. — See  pages  142  and  160. 

Ischewski's  Reagent. — For  etching:  see  page  287. 

Isobar. — The  line  in  a  diagram  showing  equal  barometric  pressure. 

Isocarb. — The  line  in  a  diagram  showing  equal  carbon  content. 

Isodictyal  Structure. — See  page  126. 

Isodimorphism. — See  page  121. 

Isolated  Crystal.— See  page  123. 

Isolation. — In  cementation :  see  page  70. 

Isomer ;  Isomeric ;  Isomeride ;  Isomerism. — See  pages  85  and  86. 

Isometric  System. — Of  crystallization:  see  page  120. 

Isomorphism. — See  page  121. 

Isomorphous  Mixture. — See  page  270. 

Isophos. — The  line  in  a  diagram  showing  equal  phosphorus  content. 

Isothei. — The  line  in  a  diagram  showing  equal  sulphur  content. 

Isotherm. — The  line  in  a  diagram  showing  equal  temperature. 

Isothermal  Freezing. — See  page  267. 

Isothermal  Transformation. — See  page  327. 

Isotropic ;  Isotropy. — See  page  330. 

Italian  Process. — See  page  141. 

-ite  (suffix). — In  chemistry:  see  page  88. 

Izod  Test.— See  page  482. 


J. 

J.  de  P.  Gage.— See  page  188. 
Jack  Shaft. — See  page  407- 

Jacket. — (i)  The  iron  sheathing  of  a  furnace;  (2)  the  brick  covering 
of  a  boiler. 

aggar  Hardness  Test. — See  page  480. 

'amb  Coke. — See  page  97. 

'apan  Lacquer. — See  page  365. 

ar  Machine. — See  page  301. 
_"arolimek  Process. — See  page  229. 
Jemmy  (Eng.). — A  short  crowbar. 
Jenkins  (C.  F.)  Process.— See  page  373. 
~ig. — See  Ore. 

ob  Pyrometer. — See  page  209. 

ockey  Weight. — Of  a  testing  machine:  see  page  469. 

og»  Jogless.— See  Curve. 

ohnson  Elastic  Limit. — See  page  470. 

ohnson  Process. — For  spheroidizing  graphite:  see  page  38. 

oint. — See  page  502. 

'oint  Board. — See  page  297. 

oint  Foliation. — See  page  1 24. 

i  oint  Strength. — See  page  282. 
Joist. — A  name  rarely  used  for  a  beam  or  I-beam. 

oly  Meldometer. — See  page  207. 

ones  and  Jones  Process. — See  page  380. 

"ones  Mixer. — See  Mixer. 

ones  Process. — (i)  For  fluid  compression:  see  page  63;  (2)  of  heat 
treatment:  see  page  232;  (3)  step  process:  see  page  142. 

ones'  Reagent. — For  etching:  see  page  287. 

'osserand  and  Jacquet  Process. — See  page  418. 

'ournal. — Of  a  roll:  see  page  403. 

"limbo. — The  cooler  for  the  cinder  notch  of  a  blast  furnace. 

ump. — (i)  In  blast  furnace  practice:  see  page  35;  (2)  in  connec- 
tion with  sheets:  see  page  430;  (3)  in  welding:  see  page  502;  (4) 
to  upset,  as  the  end  of  a  bar. 
Jumper  (Eng.).— Also  called  monkey;  (i)  a  dolly,  q.v.;  (2)  the 

sparks  from  a  ladle  of  cast  iron. 

Jump  Up  (Eng.). — Upsetting  a  bar,  etc.,  or  increasing  the  cross- 
section  by  striking  it  on  the  end. 
Junction  Shaft  (obs.). — A  spindle  in  a  rolling  mill. 
Juxtaposition  Twin. — See  page  1 24. 


247 


K.— (i)    Chemical    symbol  for  potassium   (Latin,   kallum),   q.v.; 
(2)  absolute  temperature  scale:  see  page  205. 

Kr. — Chemical  symbol  for  krypton:  see  page  84. 

K.  C.  Armor. — Krupp  cemented  armor:  see  page  9. 

Kalamein,  Kalameined.— See  page  373. 

Kamacite. — See  page  291. 

Kaolin. — See  page  396. 

Kapfl  Process.— See  page  62. 

Kathode.— See  page  89. 

Kation.— See  page  89. 

Keen  Impact  Ball  Tester. — See  page  478. 

Keep's  Test. — (i)  For  cast  iron:  see  page  483;  (2)  hardness  test: 
see  page  480. 

Keeper. — See  page  38. 

Keller  Furnace.— See  page  160. 

Keller-Leleux  Process. — See  page  160. 

Keller  Test— See  page  484. 

Kellogg  Process.— See  page  492. 

Kennedy -Morrison  Process. — See  page  233. 

Kentledge. — Pig  iron  shipped  on  a  vessel  as  ballast. 

Kern  Process. — See  page  113. 

Kernel. — See  page  126. 

Kettle. — See  page  431. 

Kick  In.— See  page  406. 

Kidney. — See  page  17. 

Kidney  Ore.— See  page  244. 

Kieselguhr  (German). — See  page  396. 

Kill.— (i)  To  hold  steel  in  a  ladle,  furnace,  or  crucible  until  no  more 
gas  is  evolved  and  it  is  perfectly  quiet;  the  steel  is  then  said  to  be 
dead:  see  page  113;   (2)  in  the  cementation  process:  see  page 
71;  (3)  of  wire:  see  page  508. 
Killeen  Distributor. — See  page  32. 
Kiln.— See  page  181. 
Kilogram  Calorie. — See  page  199. 
Kilogram-Centigrade  Heat  Unit. — See  page  199. 
Kimball  Process. — See  page  73. 
KirchhofPs  Black  Body.— See  page  207. 
Kirkstall  Bars ;  Process.— See  page  418. 
Kish.— See  Carbon. 
Kjellin-Colby  Furnace. — See  page  155. 
Kjellin  Furnace. — See  page  161. 
Kloman  Process. — See  page  418. 
Knobbled  Iron. — Iron  produced  by  the  knobbling  process :  see  page 

79- 

Knobbling  Fire  ;  Furnace  ;  Process.— See  page  79. 
Knoth  Slag  Process. — See  page  384. 
Knowle  Process.— See  page  143. 

248 


KOGEL  MILL— KURZWERNHART  249 

Kogel  Mill.— See  page  418. 

Komm  Method. — See  page  501. 

Konstantan. — See  page  209. 

Konstantinoff's  Iron -Phosphorus  Diagram. — See  page  272. 

Kourbatoff's  Reagents. — For  etching:  see  page  287. 

Kraff  and  Sauve  Process. — See  page  73. 

Krupp  Cemented  Armor. — See  page  9. 

Krupp  Furnace. — See  page  114. 

Krupp  Process. — (i)  For  armor  plate:  see  page  9;  (2)  for  fluid 
compression:  see  page  63;  (3)  for  pig  washing:  see  page  383;  (4) 
for  steel:  see  page  318. 

Kryoscopy. — Name  suggested  by  Sauveur  for  that  branch  of  metal- 
lography concerned  with  what  happens  when  metallic  alloys  are 
allowed  to  cool. 

Kumer  Process. — See  page  370. 

Kurzwernhart  and  Bertrand  Process. — See  page  61. 


L. — Longitudinal,  of  test  pieces,  etc.;  also  length. 

La. — Chemical  symbol  for  lanthanum:  see  page  84. 

Li. — Chemical  symbol  for  lithium:  see  page  84. 

Lu. — Chemical  symbol  for  lutecium :  see  page  84. 

La  ChaleassiSre  Process. — See  page  63. 

Labile  Equilibrium;  Range. — See  pages  269  and  327. 

Laboratory. — (i)  A  place  fitted  up  for  making  chemical  and  phys- 
ical tests  of  material;  (2)  the  hearth  of  an  ordinary  furnace  or  a 
blast  furnace. 

Lackawanna  Deseaming  Process. — See  page  418. 

Lacquer. — (i)  for  protection:  see  page  365;  (2)  in  wire  drawing:  see 
page  508. 

Ladle. — A  large  vessel  or  pot  for  holding,  transporting,  and  pouring 
molten  material.  Ladles  are  made  of  steel  or  iron  plates  with  a 
suitable  refractory  lining,  usually  (a)  fire-bricks  and  clay  for  steel 
and  cast  iron,  and  (6)  cast  iron  for  slag.  Those  for  cast  iron 
(iron  ladle)  and  for  slag  (slag  ladle)  are  emptied  by  tipping  them 
(top  pouring  ladle).  Those  for  steel  (steel  ladle)  are  practically 
always  provided  with  a  hole  (nozzle)  in  the  bottom  (bottom 
pouring  ladle)  through  which  the  contents  are  discharged.  In- 
the  latter  the  flow  is  regulated  by  a  stopper  consisting  of  a  steel 
rod  enclosed  in  special  hollow  fire-bricks  (sleeve  bricks);  the 
brick  on  the  lower  end  which  fits  into  the  hole  in  the  ladle  is 
called  the  stopper  head,  and  is  generally  composed  of  a  mixture  of 
graphite  and  clay;  the  upper  end  is  connected  with  a  lever  on  the 
outside  of  the  ladle.  When,  through  faulty  setting  or  some  ob- 
struction, the  stream  of  steel  cannot  be  shut  off  completely,  it  is 
called  a  running  stopper.  The  small  particle  of  steel  which  usu- 
ally solidifies  on  the  outside  of  the  nozzle,  interfering  with  the 
stream,  is  called  a  bug  or  fly.  A  bull  ladle  is  a  top-pouring  ladle  of 
small  capacity,  usually  suspended  under  a  larger  one,  to  facilitate 
the  filling  of  small  molds.  This  is  also  called  a  shank;  and  the 
verb  to  shank  or  shank  off  means  to  fill  such  a  small  ladle  from  a 
larger  one.  A  chilled  heat  is  one  which,  because  of  the  cooling  of 
the  steel,  and  particularly  of  its  solidifying  around  the  stopper 
head,  cannot  be  poured  through  the  nozzle  (except  sometimes 
by  p licking  it  with  an  iron  bar)  and  must  be  poured  over  the  top 
of  the  ladle. 

Ladle  Additions.— See  Recarburization. 
Ladle  Analysis. — See  page  82. 
Ladle  Barrow. — A  wheelbarrow  for  carrying  a  ladle  of  molten  cast 

iron  in  a  foundry. 
Ladle  Pit.— See  page  312. 
Ladle  Test— See  page  82. 
Lag. — See  page  264. 
Lagless. — See  page  269. 

Lagrange  and  Hoho  Process.— (i)  For  quenching:  see  page  230;  (2) 
for  welding:  see  page  503. 

250 


LAKE  IRON  ORE— L AUTH  MILL  251 

Lake  Iron  Ore. — See  page  244. 

Lake  Superior  Charcoal  Irons. — See  page  351. 

Lamella  (pi.  Lamellae). — See  page  126. 

Lamellar  Eutectic. — See  page  269. 

Lamellar  Martensite. — See  page  276. 

Lamellar  Structure. — See  page  126. 

Lamina  (pi.  Laminae). — See  page  126. 

Laminated.— (i)  Of  steel,  a  defect  where  there  is  a  separation  into 
layers;  (2)  composed  of  separate  sheets  or  plates  in  layers  for 
armature  cores  and  structural  parts. 

Laminated  Fracture. — See  page  178. 

Laminated  Pearlite. — See  page  274. 
.  Laminated  Structure. — See  page  126. 

Laminating  Roller. — An  adjustable  roller  in  a  rolling  mill  for  regu- 
lating the  thickness  of  sheets. 

Lamination. — See  page  124. 

Lancashire  Process. — See  page  77. 

Lancashire  Tuyere. — See  page  31. 

Lanceolate. — Lance-shaped;  tapering  gradually.     This  term  might 

be  discarded  (I.  A.  T.  M.). 
:  Landlocking  Type, — Of  freezing:  see  page  55' 

Lane  Process. — See  page  386. 

i  Langlade  Process. — For  employing  blast  furnace  gas  for  heating 
purposes;  it  consists  in  passing  it  through  water  to  reduce  the 
proportion  of  contained  steam,  and  also  to  wash  it. 
i  Langley's  Bolometer;  Radiation  Pyrometer. — See  page  207. 

Langloan  Process. — Also  called  Addie  process;  for  the  recovery  of 

tar  and  ammonia  from  the  gas  of  a  blast  furnace  using  raw  coal. 
;  Langmuir's  Film  Theory. — See  page  200. 
i  Lap;  Lap  Seam. — See  pages  405  and  426. 
I  Lap  Weld. — See  pages  489  and  502. 
\  Lap-welded  Pipe.— See  page  489. 
i  Lapper. — Of  a  sheet :  see  page  430. 
i  Large  Bessemer  Converter.— See  page  23. 
i  Large  Calorie. — See  page  199. 
{ Larkin  Process. — See  page  143. 

I  Larry. — A  car  with  a  drop  bottom,  running  on  a  track,  used  for 
carrying  ore,  coal,  etc.,  sometimes  provided  with  scales  for  weigh- 
ing the  contents;  also  called  lorry:  see  page  32. 
i  Lash-Johnson  Process. — See  page  143. 

{Latent  Heat. — (i)  General:  see  page  199;  (2)  of  fusion:  see  page 
201;  (3)  of  vaporization:  see  page  202. 

Lateral  Cleavage.— See  page  124. 

Lateral  Grain  Boundary. — See  page  283. 
( Laterite. — See  page  245. 
jLattens. — See  page  433. 

Lattice  Structure.— See  page  126. 

Lauder  (Geo.)  Process. — See  page  21. 

Laureau  Converter.— See  page  24. 

Laureau  Process. — See  page  143. 

Laurent's  Hypothesis. — See  page  70. 
'Lauth  Mill.— See  page  414. 


252  LAUTH  PROCESS— LIGHT  ALLOY 

Lauth  Process. — See  page  64. 

Lavol  Furnace. — See  page  161. 

Law's  Method. — For  sulphur  prints :  see  page  288. 

Lawrencite. — See  page  292. 

Le  Blanc's  Theory. — Of  passivity: -see  page  364. 

Le  Chatelier  Pyrometers. — (i)  Calorimetric :  see  page  207;  (2) 
couple:  see  page  209;  (3)  optical:  see  page  207;  (4)  recording :  see 
page  210;  (5)  thermoelectric:  see  page  208. 

Le  Chatelier's  Reagents. — See  page  187. 

Le  Chatelier's  Theory. — (i)  Of  equilibrium:  see  page  328;  (2)  of 
hardening:  see  page  280. 

Le  Fer  Process. — See  page  166. 

Lead.— Pb;  at.  wt.,_207;  melt,  pt.,  325°  to  335°  C.  (617°  to  649°  F.); 
sp.  gr.,  11.3.  It  is  rarely  found  in  the  uncombined  state;  usually 
in  combination  with  sulphur  or  oxygen.  The  pure  metal  is  bluish 
white  in  appearance,  and  very  soft  and  malleable;  it  is  possessed 
of  only  a  moderate  degree  of  strength.  It  is  not  found  alloyed 
with  iron  except  as  an  impurity.  In  the  molten  condition  it  is 
sometimes  used  in  tempering;  in  combination  with  tin  it  is 
employed  for  coating  thin  sheets  which  are  then  called  terne 
plates  (see  page  432). 

Lead  Burning. — Soldering:  see  page  505. 

Lead  Hardening ;  Quenching;  Tempering. — See  pages  227  and  228. 

Leading  Spindle.— See  page  407. 

Leaker. — See  page  492. 

Lean. — (i)  Of  ores :  low  grade;  having  a  small  percentage  of  metallic 
contents;  (2)  of  clays,  etc.:  lacking  in  binding  properties  or  plas- 
ticity; (3)  of  cinder:  see  page  35;  (4)  of  coal:  See  Coal. 

Least  Principal  Stress. — See  page  332. 

Leckie  Process. — See  page  143. 

Ledeburite. — See  page  277. 

Lees  Coating ;  Liquor. — See  page  508. 

Lencauchez  Process. — See  page  318. 

Lenticular. — Having  the  shape  of  a  lens  or  lentil. 

Leplay's  Hypothesis. — See  page  70. 

Lesser  Calorie. — See  page  199. 

Let  Down. — (i)  To  dilute,  e.g.,  pig  iron  is  let  down  with  scrap  to 
reduce  the  percentage  of  carbon,  etc.;  (2)  of  carbon,  to  reduce  or 
remove;  (3)  of  hardness,  to  remove  to  a  certain  exent  by  tem- 
pering. 

Letting-down  Tints. — Temper  colors:  see  page  230. 

Leucopyrite. — See  page  244. 

Levaz  Converter . — See  page  24. 

Leveling. — Of  blast:  see  page  34. 

Lever  Shears. — See  Shears. 

Liberty,  Degree  of. — See  page  327. 

Lie  Back. — See  page  36. 

Liebermeister  Process. — See  page  143. 

Lift— See  page  33. 

Lift  Hammer. — See  Hammer. 

Lifting  Table.— See  page  408.  ., 

Light  Alloy ;  Metal.— See  Alloy. 


LIGNITE— LINING  253 

Lignite.— See  Coal. 

Lilienberg  Process. — See  page  63. 

Lime. — (i)  Rarely  the  chemical  element,  calcium;  (2)  limestone,  i.e, 
the  raw  stone;  (3)  burnt  lime.or  the  oxide;  see  page  396. 

Lime  Annealing. — See  page  232. 

Lime  Bath. — See  page  507. 

Lime  Cooling. — See  page  232. 

Lime  Dinas  Brick. — See  page  395. 

Lime  Set. — See  page  35. 

Limestone. — (i)  As  a  flux:  see  page  175;  (2)  as  a  refractory:  see 
page  396- 

Liminate  Roller  (Eng.).— Same  as  laminating  roller,  q.v. 

Liming. — See  pages  342  and  507. 

Limit  Gage. — See  page  186. 

Limit  of  Linear  Elasticity ;  Proportionality. — See  page  334. 

Limiting  Concentration. — See  page  108. 

Limiting  Stress. — See  page  333. 

Limonite. — See  page  244. 

Lindenthal  Process. — See  page  318. 

Lines. — Of  a  blast  furnace:  see  page  27. 

Line  Down ;  Line  Up ;  Liner. — See  page  414. 

Lining. — (i)  Of  a  blast  furnace:  see  page  27;  (2)  in  puddling:  see 
page  376;  (3)  of  rolls  (verb) :  see  page  414. 

Lining. — The  inside  portion  or  skin;  in  a  furnace,  etc.,  that  portion 
which  comes  in  contact  with  the  charge  and  protects  the  walls 
proper  from  fusion  or  corrosion.  They  must  be  of  such  a  nature 
as  not  to  be  softened  appreciably  at  the  temperature  employed, 
and,  as  a  rule,  should  be  only  slightly  affected  (if  at  all)  by  the 
components  of  the  charge.  They  may  be  of  metal  (e.g.,  cast  iron 
for  ladles  which  hold  blast  furnace  slag),  but  generally  consist 
of  earthy  material  applied  in  a  crushed  condition,  or  as  rocks  or 
bricks.  Acid  linings  may  be  of  sand,  silicious  rocks,  or  silica 
bricks;  basic  linings,  of  crushed  burnt  dolomite,  or  magnesite 
(more  rarely  of  lime),  magnesite  bricks  or  basic  slag,  etc.;  neutral 
linings  of  coke  or  chrome  ore  either  crushed  or  in  bricks.  Linings 
for  most  types  of  furnace  are  applied  in  a  crushed  condition, 
sometimes  moistened  with  a  little  water,  or  mixed  with  a  little 
pitch  or  tar,  and  sintered  or  set  in  place  by  the  high  temperature 
to  which  they  are  exposed.  Basic  bottoms,  slag  bottoms,  cinder 
bottoms,  or  oxide  bottoms  for  heating  furnaces  consist  of  scale, 
cinder,  or  ore.  Owing  to  the  scale  which  melts  and  runs  off  the 
pieces  of  iron  or  steel  being  heated,  the  bottom  in  time  becomes 
excessively  thick,  and  is  occasionally  reduced  to  the  proper  pro- 
portion and  also  leveled  off  by  raising  the  temperature  until  a 
sufficient  amount  has  been  melted  off.  If  the  bottom  has  a  slope, 
so  that  nearly  all  the  scale  runs  out  of  the  furnace  as  fast  as  it 
forms,  it  is  called  a  dry  bottom;  if  allowed  to  collect  and  tapped 
out  only  at  intervals ,  a  wet  bottom,  or  fluid  bottom.  Acid  bottoms 
or  sand  bottoms  are  composed  of  various  grades  of  sand  which 
usually  contain  enough  impurities  to  cause  them  to  set.  Their 
thickness  is  gradually  increased  by  the  melted  scale  from  the 
metal,  in  spite  of  the  fact  that  this  causes  a  certain  amount  of  cor- 


254  LINKAGE  FORMULA— LONG  TUYERE  CONVERTER 

rosipn.  They  are  leveled  off  by  throwing  in  a  little  coke  and  b} 
raising  the  temperature,  the  joint  action  serving  to  melt  and  flu^ 
away  the  upper  layers.  A  coke  bottom  is  made  of  crushed  cok4 
rammed  into  place,  usually  mixed  with  a  little  cinder  or  tar  t<| 
cause  it  to  set  when  heated;  in  the  case  of  soaking  pits,  crusheq 
coke  or  coke  dust  is  loosely  thrown  on  the  bottom  of  the  pits. 

Linkage  Formula. — See  page  86. 

Lintel  Plate.— See  page  27. 

Lip. — The  depression  in  the  edge  of  a  ladle  through  which  the  con- 
tents are  poured. 

Liquation. — See  pages  55  and  68. 

Liquid  Blacking. — See  page  298. 

Liquid  Cements. — See  pages  67  and  69. 

Liquid  Compression. — See  page  63. 

Liquid  Contraction. — See  page  53. 

Liquid  Crystal. — See  page  123. 

Liquid  Furnace. — Containing  a  molten  bath,  such  as  a  fused  salt  or 
metal,  in  _  which  the  object  is  submerged;  used  particularly  in 
heat  treating  work. 

Liquid  Solution. — See  page  270. 

Liquid  Squeezed. — See  page  64. 

Liquid  State.— See  page  81. 

Liquidoid. — See  page  270. 

Liquidus ;  Liquidus  Curve. — See  page  268. 

Liquor -Bright  Process. — See  page  508. 

List;  List  Pot. — See  page  432. 

Lithosiderite. — See  page  291. 

Littoral  Region. — In  the  freezing  of  alloys :  see  page  54. 

Live  Load. — See  page  468. 

Live  Pass. — See  page  405. 

Live  Roller. — See  page  407. 

Lively. — Of  molten  steel  in  the  ladle  or  molds:  bubbling  or  rising 
to  a  certain  extent,  due  to  the  evolution  of  gas. 

Load. — See  page  332. 

Loading  Test. — See  page  477. 

Loam. — See  pages  296  and  396. 

Loam  Brick;  Cake. — A  slab  or  cake  of  loam  used  in  molding. 

Loam  Molding. — See  page  300. 

Local  Elastic  Limit. — See  page  282. 

Local  Elongation. — See  page  474. 

Localized  Corrosion;  Selective  Corrosion. — See  page  106. 

Lock  Joint. — A  joint  or  seam  in  tubes,'  sheets,  cans,  etc.,  produced 
by  folding  the  edges  over  together. 

Locus  (pi.  Loci). — See  Curve. 

Lodestone. — See  page  244. 

Logometer. — See  page  208. 

Lohmann  Bath;  Process;  Lohmannizing. — See  page  373. 

Lollingite. — See  page  244. 

Lombardy  Process. — See  page  78. 

Long-tailed  Monkey. — See  Monkey. 

Long  Ton. — See  Ton. 

Long  Tuyere  Converter. — See  page  24. 


LONGITUDINAL  ROLLING— LUTE  255 

Longitudinal  Rolling. — See  page  414. 

Longitudinal  Seam. — See  Seam. 

Longitudinal  Test  Piece. — See  page  469. 

Look  over  a  Heat. — In  crucible  practice :  see  page  114. 

Loop.— See  page  135. 

Looping ;  Looping  Mill.— See  page  416. 

Lorry. — See  Larry. 

Lost  Head. — See  page  299. 

Lost  Pass. — See  page  405. 

Lost-wax  Process. — See  page  301. 

Loup. — See  page  135. 

Low. — Of  springs  which  upon  testing  are  more  or  less  flattened  (not 
good). 

Low  Carbon  Steel. — See  page  455. 

Low  Gage.— See  page  186. 

Low  Grade. — Sometimes  used  for  low  carbon. 

Low  Grade  Fireclays. — See  page  396. 

Low  Heat  Treatment. — In  the  Taylor-White  process:  see  page  446. 

Low  Phosphorus  Pig. — See  pages  344  and  346. 

Low  Process. — See  page  118. 

Low  Steel  (rare). — Soft  or  low-carbon  steel. 

Low  Temper  Steel.— See  Temper. 

Lower  Freezing  Point. — See  page  267. 

Lowering  Temperature. — See  page  447. 

Lucas  Process. — See  page  143. 

Liiders  Lines.— See  page  283. 

Ludlum  Furnace. — See  page  162. 

Ludwik's  Method. — For  determining  hardness:  see  page  478. 

Lug. — A  knob  or  projection  on  a  smooth  surface  used  for  picking  it 
up,  etc. 

Lugging  (Eng.). — Of  material  which  tears  or  does  not  cut  crisply. 

Lump. — (i)  The  ball  from  a  direct  process :  see  page  135;  (2)  a  prod- 
uct in  puddling  (obs.):  see  page  378;  (3)  a  piece  of  ganister,  etc., 
forming  part  of  a  refractory  lining:  see  page  395. 

Lumpy. — Of  rails,  or  bars,  short  kinked  or  wavy. 

Lurmann's  Closed  Front  Arrangement. — See  page  32. 

Lunnann  Front.— See  page  32. 

Luster ;  Lustre. — A  term  used  in  describing  the  character  of  the 
reflections  obtained  from  the  fractured  surfaces  of  minerals  and 
rocks  (I.A.T.M.). 

Lute. — A  mixture  of  fireclay,  etc.,  used  to  seal  up  cracks  when  heat 
is  to  be  applied,  e.g.,  between  a  crucible  and  its  cover  to  make  an 
air-tight  fit;  also  the  operation. 


M 

Mg. — Chemical  symbol  for  magnesium,  q.v. 

Mn. — Chemical  symbol  for  manganese,  q.v. 

Mo. — Chemical  symbol  for  molybdenum,  q.v, 

M.  C.  B. — Master  Car  Builders  (association). 

M.  P.— Melting  point. 

McCance's  Interstrain  Theory. — Of  hardening:  see  page  281. 

McClenahan  Process.— See  Flux. 

McCloud  Process.- — See  page  419. 

McConnell  (Niven)  Process. — See  page  318. 

McDonald  Distributor. — See  page  32. 

McHaffie  Process. — See  page  258. 

McKenna's  Formula. — For  quality :  see  page  340. 

McKenna  Process. — See  page  419. 

Machine  Cast  Pig. — See  page  342. 

Machine  Molding. — See  page  301. 

Machine  Puddled. — Wrought  iron  made  in  a  mechanical  puddler : 
see  page  379. 

Machining.— See  Cold  Working. 

Macintosh  Process. — See  page  73. 

Macle. — See  page  124. 

Macro-Metallography.— See  page  263. 

Macroscopic. — Or  megascopic :  a  term  used  in  contradistinction  to 
microscopic,  to  imply  that  the  character  in  question  is  visible  to 
the  naked  eye  (I.  A.  T.  M.). 

Macroscopic  Analysis. — See  page  284. 

Macroscopic  Etching. — See  page  286. 

Macroscopic  Metallography. — See  page  263. 

Macroscopic  Strain.— See  page  280. 

Macroscopic  Structure. — Or  macrostructure :  see  page  289. 

Macroscopically  Amorphous. — See  page  127. 

Macrostructure.— See  page  289. 

Macrostructure  Etching.— See  page  286. 

Magdolite. — See  page  397. 

Magma. — See  page  125. 

Magnesia. — (i)  As  a  flux:  see  page  175;  (2)  as  a  refractory;  see  page 
396. 

Magnesia  Brick. — See  page  397. 

Magnesian  Limestone. — See  page  397. 

Magnesite  ;  Magnesite  Brick. — See  page  396. 

Magnesium. — Mg.;  at.  wt.,  24;  melt,  pt.,  632.6°  C.  (1141.9°  F.); 
sp.  gr.,  1.7.     It  is  a  silvery  white  metal  with  a  very  strong  affinity 
for  oxygen,  for  which  reason  it  is  employed  as  a  deoxidizer  for 
copper;  in  the  case  of  steel,  however,  it  has  not  proved  to  be  as 
satisfactory  as  aluminum,  as  the  reaction  is  very  violent. 
Magnet  Steel. — See  page  450. 
Magnetic  Alloy. — See  Alloy. 
Magnetic  Analysis. — See  page  284. 


MAGNETIC  CONCENTRATION—MALLEABLE      257 

Magnetic  Concentration. — See  Ore. 

Magnetic  Hardness. — See  page  450. 

Magnetic  Iron  Ore. — See  page  244. 

Magnetic  Method. — For  determining  critical  points:  see  page  266. 

Magnetic  Oxide  Theory. — Of  puddling:  see  page  378. 

Magnetic  Pyrites. — See  page  245. 

Magnetic  Separation. — See  Ore. 

Magnetic  Steel. — See  page  450. 

Magnetic  Transformation^ — See  page  264. 

Magnetite. — See  page  244. 

Magnite. — See  page  399. 

Magnobrent. — See  page  399. 

Main  Spindle. — See  page  407. 

Major  Calorie. — See  page  199. 

Major  Shrinkage. — See  page  54. 

Make  Bottom. — See  page  313. 

Make  a  Cast ;  Heat. — Melting  iron  in  a  cupola  for  foundry  work. 

Malleability. — See  page  331. 

Malleable. — (i)  Malleable  castings  (#.*>.);  (2)  pig  iron  suitable  for 
making  into  malleable  castings:  see  page  346. 

Malleable  Bessemer. — See  page  346. 

Malleable  Cast  Iron. — See  below. 

Malleable  Castings. — Also  called  malleable  iron,  malleable  cast 
iron,  malleable,  or  malleablized  cast  iron;  more  rarely  temper 
(tempered)  castings  or  run  steel.  They  are  castings  in  which  the 
combined  carbon  of  white  cast  iron  has  been  converted  into  an 
amorphous,  uncombined  condition  by  special  heat  treatment 
without  fusion,  leaving  the  iron  soft  and  to  a  certain  extent  mal- 
leable. The  process  was  discovered  by  Reaumur,  and  hence  the 
product  was  at  one  time  known  as  Reaumur  iron.  The  carbon 
exists  in  small  spots  or  patches  which  do  not  break  up  the  con- 
tinuity of  the  iron  matrix  nearly  so  much  as  the  large  thin 
plates  of  graphite  in  ordinary  gray  cast  iron  which  serve  as  cleav- 
age planes.  This  form  of  carbon  is  termed  temper  carbon  or 
temper  graphite,  more  rarely  annealing  carbon. 

The  process  consists  essentially  in  heating  white  cast  iron  cast- 
ings (hard  castings),  in  which  practically  all  the  carbon  is  in 
the  combined  condition,  to  a  temperature  above  about  750°  C. 
(1380°  F.),  but  below  its  melting  point,  say  under  1100°  C.  (2010° 
F.;,  when  the  conversion  of  the  carbon  to  the  amorphous  uncom- 
bined condition  takes  place,  apparently  due  principally  to  the 
silicon  (assisted  by  the  heat)  of  which  a  certain  percentage  must 
be  present.  If  the  castings  are  heated  too  hot,  and  in  conse- 
quence become  softened  and  deformed,  they  are  said  to  fall.  A 
mixture  of  pig  iron  to  give  the  desired  composition  is  melted  in  a 
cupola,  an  air  furnace  (reverberatory),  x>r  a  furnace  similar  to 
that  used  in  the  open  hearth  process,  and  is  then  poured  into  the 
molds.  When  an  open  hearth  furnace  is  used,  and  it  is  first  put 
into  service,  the  initial  heat,  called  a  pill  heat,  is  usually  cast  into 
pigs  for  remelting,  as  it  is  not  certain  whether  the  metal  will  be 
satisfactory.  When  the  charge  consists  chiefly  of  runners  and 
defective  castings,  it  is  termed  a  sprue  heat. 
17 


258          MALLEABLE  COKE  IRON— MANGANESE 

The  castings  are  usually  less  than  an  inch  in  thickness,  so  the 
cooling  will  be  sufficiently  rapid  to  prevent  the  formation  of 
graphite.  The  original  shrinkage  is  about  double  that  of  gray 
castings,  but  about  half  of  this  is  recovered  upon  annealing. 
After  cleaning,  they  are  packed  in  some  material,  such  as  ore  or 
clay,  contained  in  a  box  called  a  sagger  or  annealing  pot,  to  pro- 
tect them  from  the  air  and  so  prevent  excessive  formation  of 
scale  which  would  produce  what  are  termed  scaled  castings. 
Reaumur's  process  ("of  softening  cast. iron"),  which  is  also  that 
used  principally  abroad  (hence,  European  or  old  European  proc- 
ess), employs  new  iron  ore  which  causes,  in  the  case  of  thin 
castings,  most  of  the  carbon  to  be  oxidized  and  removed  (decar- 
burizing  process),  so  that,  on  breaking,  the  fracture  is  nearly 
white  throughout  (white-heart  malleable  or  casting).  In  this 
country  (American  process)  the  packing  material  is  generally 
made  up  of  two  or  three  parts  of  old  ore  (burnt  ore  or  spent  ore) , 
which  has  only  a  slight  oxidizing  effect,  and  one  part  of  new 
ore.  This  restricts  the  oxidation  of  the  carbon  to  that  in  the 
outer  layers,  so  that  the  carbon  in  the  interior  is  simply  changed 
to  the  amorphous  condition,  and  the  fracture  shows  a  white 
outside  skin  with  a  black  interior,  from  which  comes  the  name 
black-heart  malleable  or  casting. 

The  heating  operation  (annealing)  requires  a  number  of  days 
and  is  performed  in  an  annealing  furnace  or  oven,  the  boxes  being 
arranged  so  the  flame  may  play  around  them  as  completely  as 
possible;  the  flame  usually  enters  at  the  top  of  the  furnace  and 
leaves  at  the  bottom  along  the  side,  and  then  passes  through 
flues  underneath. 

In  the  Terreault  and  Hilzinger  process  the  cast  iron  is  melted 
in  crucibles  with  about  0.25%  of  sodium  chloride  and  the  castings 
are  poured  in  the  ordinary  way.  They  are  then  placed  in  anneal- 
ing boxes  and  packed  in  scale  which  has  first  been  soaked  in  a  7.5 
%  solution  of  ammonia  (/.  /.  &  S.  I.,  1911, 1,  605).  The  McHaf- 
fie  process  does  not  appear  to  differ  essentially  from  ordinary 
practice. 

Malleable  Coke  Iron. — See  page  340. 

Malleable  Iron. — (i)  Wrought  iron;  (2)  malleable  cast  iron:  see 
above;  (3)  pig  iron  suitable  for  making  into  malleable  castings: 
see  page  346. 

Malleable  Pig  Iron. — See  page  344. 

Malleable  Wrought  Iron. — Wrought  iron,  q.v. 

Malleablized  Cast  Iron. — See  page  257. 

Manganese. — Mn;  at.  wt.,  55;  melt,  pt.,  1207°  C.  (2200°  F.);sp. 
gr.,  7.42.  It  is  found  in  combination  with  oxygen,  and  usually 
in  conjunction  with  iron.  The  pure  metal  has  a  grayish  white 
color,  with  a  slight  tinge  of  red,  and  is  hard  and  brittle.  It  is 
obtained  as  an  alloy  with  iron  called  ferro-manganese  or  spiegel, 
rarely  manganese  (see  page  352),  and  very  recently  with  silicon, 
called  silico -spiegel  (see  page  354).  It  has  a  stronger  affinity  for 
oxygen  and  sulphur  than  has  iron.  Next  to  carbon  it  is  the  most 
important  constituent  of  steel.  In  ordinary  amounts  its  most 
valuable  property  is  in  removing  oxygen  existing  in  the  steel 


MANGANESE  ADDITIONS— MARQUETTE          259 

either  as  a  gas  or  in  direct  combination  as  oxide  (see  page  393). 
As  a  desulphurizing  agent,  see  page  386.  In  ordinary  steel  the 
manganese  varies  from  about  0.30  to  1.00%;  below  0.30  the 
removal  of  oxygen  does  not  seem  to  be  sufficiently  thorough  (ex- 
cept with  steel  made  in  a  crucible  or  in  an  electric  furnace,  etc.), 
while  above  1.50%,  and  up  to  about  6  or  7%,  the  hardness  and 
the  brittleness  under  shock  increase  so  rapidly  that  the  material  is 
not  of  commercial  value.  Above  the  limit  mentioned,  and  up  to 
about  15%,  a  curious  reversal  takes  place,  the  metal  remaining 
very  hard,  but  becoming  tough  upon  suitable  treatment;  this 
metal  is  called  manganese  steel  (see  page  451).  Above  about  16 
or  17%  the  metal  becomes  more  brittle  again.  Manganese  in 
increasing  amounts  raises  the  saturation  point  of  iron  for  carbon. 
For  influence  on  corrosion :  see  page  366. 

Manganese  Additions. — See  Recarburization. 

Manganese  Carbide. — See  page  279. 

Manganese  Carbon  Iron ;  Steel. — A  term  rarely  employed  for  ordi- 
nary steel  or  cast  iron  containing  not  over  about  1.50%  or  2.00% 
of  manganese,  to  distinguish  it  from  manganese  steel  which  has 
over  about  10  %  of  manganese. 

Manganese  Ore. — See  page  245. 

Manganese  Silicate. — See  page  279. 

Manganese  Spot. — See  Hard  Spot. 

Manganese  Steel. — See  page  451. 

Manganese  Steel  Lines.  — See  page  127. 

Manganese  Sulphide. — See  pages  279  and  289. 

Manganic. — Manganese  in  chemical  compounds  having  the  higher 
valence  III. 

Manganiferous. — Containing  or  carrying  manganese. 

Manganiferous  Cementite. — See  page  279. 

Manganiferous  Iron  Ore. — See  page  245. 

Manganin. — See  page  209. 

Mangano-Ferrite. — See  page  272. 

Mangano-Magnesian  Magnetite. — See  page  244. 

Manganous. — Manganese  in  chemical  compounds  having  the  lower 
valence  II. 

Mangle  (Eng.). — A  set  of  straightening  rolls  for  plates,  etc. 

Manipulator. — See  page  411. 

Manne smarm' s  Equilibrium  Diagram. — See  page  272. 

Mannesmann  Process. — See  page  490. 

Mantle  (Mantel)  Ring. — See  page  27. 

Manufacturing  Coal. — See  Coal. 

Many-blow  Test. — See  page  482. 

Marcasite. — See  page  245. 

Marel  Brothers  Process. — See  page  64. 

Margarite  Structure. — See  page  125. 

Mariotte's  Law.— See  Gas. 

Marking. — Branding :  where  rolls  are  engraved  and  brand  appears 
on  rolled  piece  in  raised  characters ;  stamping :  where  characters 
are  forced  into  the  surface.  Both  are  called  marking  which  also 
includes  painting,  tagging  or  other  means  of  identification. 

Marquette  d'Encrenee  (Fr.).— See  page  135. 


260   MARTENS'  REAGENTS— MECHANICAL  HARDNESS 

Martens  and  Heyn's  Reagent— For  etching:  see  page  288. 

Martens'  Reagents. — For  etching:  see  page  287. 

Martens  Test. — For  hardness :  see  page  480. 
^  Martensite. — See  pages  275  and  276. 

Martensite  Carbon. — See  page  276. 

Martensite  Steel.' — Steel  containing  gamma  iron. 

Martensitic  Special  Steels.— See  page  445. 

Martensitization. — See  page  276. 

Martensitizing  Methods  of  Hardening. — See  page  279. 

Martien  Process. — See  page  386. 

Martin  and  Beavis  Mill. — See  page  420. 

Martin  Furnace. — See  page  310. 

Martin  Process. — See  page  310. 

Martin-Siemens  Process. — See  page  310. 

Martin-Siemens  Steel. — Open  hearth  steel. 

Marti te. — See  page  244. 

Mass  Effect. — On  the  physical  condition  of  material:  see  page  219. 

Massenez  Process. — (i)  For  steel:  seepage  22;  (2)  for  desulphur- 
izing: see  page  386. 

Massive. — Amorphous;  not  crystalline. 

Massive  Cementite. — See  page  273. 

Massive  Ferrite. — See  page  272. 

Massive  Magnesite. — See  page  397. 

Massive  Structure. — See  page  125. 

Massut  (Russian). — The  residue  from  the  distillation  of  crude 
petroleum  at  a  temperature  of  about  300°  C.  (572°  F.);  it  has  a 
specific  gravity  of  about  0.90  to  0.91,  and  burns  in  an  open  vessel 
at  about  100°  to  130°  C.  (212°  to  266°  F.);  it  has  a  calorific  power 
of  about  10,000  calories,  and  is  composed  of  about  87  %  of  carbon, 
12  %  of  hydrogen,  and  i  %  of  oxygen. 

Matcher ;  Matching. — See  page  430. 

Mathias  Deseaming  Process. — See  page  418. 

Matrix. — (i)  The  die  or  mold  used  to  give  the  desired  form  to  an 
object;  (2)  in  metallography,  the  ground  mass  or  principal  sub- 
stance in  which  a  constituent  is  embedded. 

Matter. — (i)  Definition:  see  page  81;  (2)  state  of:  see  page  81. 

Matthiessen  Process. — See  page  143. 

Matweieff's  Reagent. — For  etching:  see  page  287. 

Maul. — A  large  wooden  hammer  used  for  flattening  plates  while 
hot;  a  beetle. 

Maximum  Fiber  Stress. — See  page  337. 

Maximum  Load;  Stress. — See  page  335. 

Maximum  Temperature. — And  grain  size;  see  page  213. 

Meager  Coal.— See  Coal. 

Mean. — Average  or  normal. 

Mean  Calorie. — See  page  199. 

Mean  Stress. — See  page  333. 

Mechanical  Amorphizing. — See  page  282. 

Mechanical  Brittleness. — See  Brittleness. 

Mechanical  Equivalent  of  Heat. — See  page  204. 

Mechanical  Hardness. — See  page  331. 


MECHANICAL" IMPURITY— MERCADER  AXLE    261 

Mechanical  Impurity. — See  Impurity. 

Mechanical  Methods  of  Etching. — See  page  286. 

Mechanical  Mixture. — See  page  83. 

Mechanical  Process. — Working,  as  rolling  or  forging,  as  distin- 
guished from  some  chemical  or  metallurgical  process. 

Mechanical  Puddler;  Puddling  Furnaces;  Rabble. — See  page  379. 

Mechanical  Refining. — Improving  the  quality  of  steel  or  wrought 
iron  by  reducing  the  size  of  the  grain  by  working  the  metal 
while  cooling  until  the  temperature  has  about  reached  the  critical 
point;  sometimes  called  hammer  refining:  See  page  216. 

Mechanical  Stirrer. — See  page  379. 

Mechanical  Thermometer. — See  page  205. 

Mechanical  Tinning  Pot. — See  page  432. 

Mechanical  Treatment. — For  producing  solid  castings:  see  page 

59- 

Mechanical  Twin. — See  page  124. 
Mechanical  Working. — Usually  referred  to  in  connection  with  its 

effect  on  the  physical  properties  as  distinguished  from  that  pro- 
duced by  heat  treatment  alone. 
Mechanically  Combined  Water. — See  Water. 
Mechanico-chemical  Methods  of  Etching. — See  page  288. 
Medicine  Room. — See  page  115. 
Medium  Carbon  Steel. — See  page  455. 
Medium  Grade  Fireclays. — See  page  396. 
Medium  Steel. — See  page  455. 
Medium  Temper  Steel.— See  Temper. 
Megascopic. — Macroscopic,  q.v. 
Meiler.— See  Charcoal. 
Melanterite. — See  page  245. 
Meldometer,  Joly. — See  page  207. 
Mellen  Rod-casting  Process. — See  page  65. 
Melloni  Thermopile. — See  page  207. 
Melt. — (i)  To  fuse;  (2)  a  heat  or  charge  of  steel. 
Melt  High;  Low. — See  page  314. 
Melter. — The  man  in  charge  of  a  crucible  furnace,  cupola,  or  open 

hearth  furnace. 
Melting. — See  page  201. 

Melting  Down  Refinery ;  Melting  Finery. — See  page  383. 
Melting  Furnace. — Any  furnace  in  which  metals  can  be  melted, 

more  especially  cast  iron. 
Melting  Heat.— See  page  71. 

Melting  Hole. — Of  a  crucible  furnace:  see  page  114. 
Melting  House  (Eng.). — A  department  in  a. steel  works  for  making 

crucible  steel. 

Melting  Point. — See  page  201. 
Melting  Point  Curve. — See  Curve. 
Melting  Point  Pyrometry. — See  page  209. 
Melting  Refinery.— See  page  383. 
Menacconite. — See  page  245. 
Mendelejeff's  Periodic  Law. — See  page  85. 
Mercader  Hollow -pressed  Axle. — An  axle  produced  by  a  process 

somewhat  similar  to  the  Erhardt  process.     A  heated,  round 


262       MERCHANT— METALLOGRAPHIC  EXAMINATION 

blank,  after  removal  of  the  scale  in  a  set  of  cross  rolls,  is  placed  in 
a  die  having  the  shape  of  the  finished  axle,  and  a  punch  is  forced 
(hydraulically)  into  each  end,  to  a  depth  sufficient  to  displace 
enough  metal  to  fill  out  the  die  and  also  upset  the  metal  at  the  end 
for  the  collars.  A  few  axles  were  made  and  placed  in  service, 
but  the  process  never  really  got  beyond  the  experimental  stage, 
due  principally  to  difficulty  in  keeping  the  punches  concentric 
with  the  axis  of  the  axle. 

Merchant. — In  general,  an  adjective  used  to  denote  material  which 
is  finished  or  for  sale,  also  the  appliances  for  its  production. 

Merchant  Bar. — See  page  3  78. 

Merchant  Furnace. — See  page  39. 

Merchant  Mill. — See  page  409. 

Mercurial  (Mercury)  Thermometer. — See  page  205. 

Merging. — See  page  120. 

Merging  of  Critical  Points. — See  page  264. 

Merit  Number. — See  page  340. 

Meritens  (A.  de  )Process. — See  page  369. 

Memman's  Formulae. — For  tensile  strength:  see  page  338. 

Merrit  Plate. — See  page  135. 

Mesh  Structure. — See  page  126. 

Mesosiderite. — See  page  291. 

Mesure  and  Nouel's  Pyroscope. — See  page  208. 

Metacryst. — See  page  122. 

Meta -Element. — See  page  81. 

Metal. — (i)  Any  metallic  element  in  its  reduced  form:  see  page  83; 
(2)  pig  iron  or  steel,  more  particularly  the  former,  when  the 
meaning  is  obvious;  (3)  the  product  of  a  refinery:  see  page  383. 

Metal  Notch. — See  page  32. 

Metal  Sponge.— See  Alloy. 

Metal  Spraying.— See  page  373. 

Metal  Stove. — See  page  34. 

Metallic. — Having  the  properties  of  a  metal,  more  especially  the 
physical  ones,  such  as  luster,  opacity,  ductility,  etc. 

Metallic  Alloy.— See  Alloy. 

Metallic  Cementation. — See  pages  66  and  370. 

Metallic  Coating. — See  page  370. 

Metallic  Fog.— See  page  128. 

Metallic  Luster.— See  page  83. 

Metallic  Nickel.— See  page  353. 

Metallic  Solid  Solutions. — See  page  270. 

Metallic  Thermometer. — See  page  205. 

Metallicity;  Metalleity. — Condition  or  quality  of  being  metallic. 

Metallifacture    (obs.). — Metallurgy. 

Metalliferous. — Containing  a  metal,  as  an  ore  or  deposit. 

Metallify. — Smelt  or  reduce  into  a  metal. 

Metalline.— Metallic. 

Metallize. — (i)  To  coat  with  a  metal;  (2)  to  convert  or  reduce  to 
the  metallic  state,  as  an  ore;  (3)  to  impregnate  with  metallic  or 
mineral  substances,  as  wood. 

Metallographic  Examination.— See  page  284. 


METALLOGRAPHY  263 

Metallographic    Method. — For    determining    critical    points:  see 

page  265. 

Metallography. — That  branch  of  metallurgy  which  treats  of  the 
constitution  and  the  structure  of  metals  and  alloys,  and  their 
relation  to  the  physical  properties.  This  definition  covers  the 
very  broad  field  which  it  is  now  recognized  that  metallography 
occupies,  and  any  method  of  research  may  be  employed.  When 
it  was  a  comparatively  new  science,  however,  it  was  familiarly 
supposed  to  be  concerned  principally  with  the  visual  exami- 
nation of  the  structure  of  metals  and  hence  was  divided  into 
microscopic  or  micrometallography  where  the  microscope  was 
employed  to  secure  high  magnifications,  and  megascopic, 
macroscopic  or  macrometallography  where  the  naked  eye  or  very 
low  magnifications  were  used. 

The  following  are  briefly  the  principal  events,  in  their  chrono- 
logical order,  which  are  responsible  for  our  present  knowledge  of 
the  subject : 

1864.  Sorby  (British  Assoc.)  published  his  work  on  the 
microscopic  examination  of  iron  and  steel,  which  he  had  com- 
menced the  preceding  year.  This  did  not  bear  any  fruit  until 
after  1887,  in  which  year  he  read,  by  request,  a  paper  on  the  sub- 
ject before  the  Iron  and  Steel  Institute. 

1869.  Gore  (Proc.  Roy.  Soc.)  published  the  results  of  his 
experiments  on  the  dilatation  of  steel  at  high  temperatures.  The 
method  employed  was  a  wire  stretched  horizontally  which,  by 
means  of  a  series  of  levers,  indicated  the  amount  of  expansion  or 
contraction  during  heating"  or  cooling.  At  a  dark  red,  he  found 
on  cooling  a  greater  dilatation  than  immediately  above  or  below' 
that  temperature.  He  called  this  phenomenon  recalescence, 
because  of  the  momentary  brightening  which  accompanied  it.  He 
did  not,  however,  observe  the  reverse  effect  during  heating. 

1873.  Barrett  (Phil.  Mag.)  carefully  checked  the  work  of  Gore 
and  found  the  reverse  effect  occurred  during  heating  at  nearly  the 
same  temperature  as  during  cooling.  He  noted  that  this  point 
was  slight  in  the  case  of  soft  steels. 

1880.  Hogg  stated  that  quenched  steel  showed  less  carbon 
by  the  Eggertz  color  method  than  the  same  steel  annealed.  About 
this  time  iron  carbide,  Fe3C,  was  isolated  from  annealed  steel  by 
Weyl,  Abel  and  Mueller. 

1885.  Osmond  and  Werth  (Ann.  d.  Mines')  published  their 
paper  on  the  cellular  theory  of  steel. 

In  the  years  immediately  following  Osmond  (Mem.  Artil.  et 
Mar.}  gave  the  results  of  his  experiments  on  the  transformation  of 
iron  and  carbon,  employing  cooling  curves  obtained  by  means  of  a 
Le  Chatelier  electrothermic  pyrometer. 

1886.  Pionchon   made  experiments  on  the  specific  heats  at 
different   temperatures    certain  seeming  anomalies  pointing  to 
allotropic  transformations. 

1890.  H.  Le  Chatelier  published  variations  in  electrical  resist- 
ance at  different  temperatures,  confirming  the  resultapobtained 
by  other  methods. 

1895.     Osmond  published   (Butt.   Soc.   d'Enc.)   his  classical 


264  METALLOGRAPHY 

monograph  on  the  "General  Method  for  the  Microscopical  Exami- 
nation of  Carbon  Steels." 

1899.  Roberts- Austen  plotted  the  first  iron-carbon  diagram, 
corrected  and  amplified  by  Roozeboom,  the  following  year,  on  the 
basis  of  the  phase  rule. 

Other  investigators  to  whom  particular  tribute  must  be  paid 
are  Howe,  Sauveur,  Stead  and  Arnold. 

Iron  or  steel,  when  solid,  consists  of  grains  or  crystals  the  size 
of  which  depends  upon  the  heat  treatment  and  the  mechanical 
treatment  they  have  received.  Ordinarily  iron  or  steel  is  not 
homogeneous,  but  is  composed  of  a  variety  of  substances  or 
constituents  (in  the  same  way  that  rocks  are  made  up  of  different 
minerals)  depending  upon  (a)  the  proximate  chemical  composi- 
tion, and  (6)  the  heat  treatment.  "The  microscopic  constitu- 
ents of  steels  are  divided  into  those  that  are  chemically  homogene- 
ous (metaral)  and  those  that  are  chemically  heterogeneous  (ag- 
gregate) "(I.  A.  T.  M.). 

Allotropic  Modifications. — Metallography  is  based  on  Os- 
mond's demonstration  (Osmond's  theory,  allotropic  theory)  that 
iron  is  susceptible  of  three  allotropic  varieties  or  modifications 
known  respectively  as  alpha  (a)  iron,  beta  (/3)  iron,  and  gamma 
(7)  iron,  each  being  normal  for  a  given  range  of  temperature  and 
conditions. 

Transformations  and  Critical  Points. — It  has  been  known  for 
some  time  that  the  rate  of  cooling  or  heating  does  not  always 
proceed  uniformly,  but  that  at  certain  temperatures  (which  may 
vary  with  different  compositions)  retardations  occur,  and  these 
are  termed  arrestation  points,  critical  points  (critical  tempera- 
tures), transformation  points,  or  transition  points.  These  are 
caused  by  physical  changes  whereby  heat  is  liberated  on  cooling 
and  absorbed  on  heating.  There  are  three  principal  critical 
points  for  iron  designated  A\,  A2,  and  At,  A\  being  at  the  lowest 
temperature.  On  account  of  molecular  inertia  or  lag  (Howe), 
the  changes  occur  at  lower  temperatures  on  cooling  than  on  heat- 
ing unless  the  rates  are  infinitely  slow.  The  transformation  at 
A  2  is  also  referred  to  as  the  magnetic  transformation.  To  indi- 
cate such  conditions  Howe  has  called  these  theoretical  points 
Ae,  etc.,  (e  standing  for  equilibrium).  In  certain  grades  of  iron 
two  or  even  all  three  points  may  occur  at  the  same  temperature 
(merging  of  the  critical  points),  and  to  show  this  they  are  written, 
e.g.)  Ar3_2,  Ar 3-2-1.  For  hypereutectoid  steel  Sauveur  suggests 
for  the  upper  critical  point  "the  symbol  Acm  (Arcm  on  cooling 
and  Accm  on  heating),  cm  standing  for  cementite.  At  least  one 
writer,  however,  has  designated  this  point  on  cooling  by  the  nota- 
tion Armc,  me  standing  for  massive  cementite"  (Sauveur,  Metal- 
lography, 1 66).  A  point  found  by  Roberts- Austen  between  550 
and  600°  C.  for  iron  and  soft  steel  he  called  Ar0.  "  Roberts-Aus- 
ten detected  another  evolution  of  heat  in  pure  iron  between  450 
and  500°  C.,  the  existence  of  which  he  ascribed  to  the  presence  of 
hydrogen  (hydrogen  point)  resulting  in  a  separation  of  hydroxide 
of  iron  taking  place  at  this  critical  point.  Finally  the  same 
observer  described  one  more  slight  evolution  of  heat  in  pure  iron 


METALLOGRAPHY  265 

at  about  270°  C.  which  he  tentatively  ascribed  to  the  formation  of 
an  iron — iron  hydroxide  eutectic  (ibid.,  167).  Brinell  used  the 
letter  W  for  the  upper  point  and  V  for  the  lower  point  of  the 
hardening  or  transformation.  Tschernoff  used  the  letter  A  to 
indicate  the  temperature  above  which  hardening  could  be  pro- 
duced by  quenching,  but  below  which  hardening  could  not  be  pro- 
duced. In  some  cases  a  retardation  may  occur  not  simply  at  or 
near  one  temperature  but  over  a  more  or  less  extended  range 
(critical  range  or  interval,  etc.).  The  rate  at  which  a  transforma- 
tion occurs  is  known  as  the  speed  or  velocity  of  transformation. 
In  some  cases  while  cooling  through  Ari,  there  is  such  a  liberation 
of  heat  that  the  temperature  may  be  raised  slightly  and  in  the 
dark  a  sudden  glowing  can  be  observed;  this  phenomenon  is 
termed  recalescence  (the  piece  is  said  to  recalesce)  or  rarely 
calescence  or  Gore's  phenomenon,  and  the  temperature  at  which 
it  occurs,  the  recalescent  point;  to  indicate  the  reverse  effect  on 
heating,  it  is  sometimes  called  the  decalescent  point,  absorption 
point  or  temperature,  and  without  reference  to  heating  or  cooling 
respectively  the  calescent  point.  At  this  point  a  softening  action 
takes  place  which  is  shown  by  Coffin's  bend:  if  an  iron  bar, 
heated  above  Ari  is  supported  at  its  ends  only,  and  then  allowed 
to  cool,  when'  the  temperature  reaches  Ari  it  will  bend,  although 
this  does  not  occur  just  above  or  just  below.  Alloys  (and  trans- 
formations), where  there  is  a  very  wide  interval  (temperature 
interval,  hysteresis  temperature,  hysteresis  gap)  between  the 
temperature  of  the  critical  point  on  heating  and  cooling  are  said 
to  be  non-reversible  or  irreversible ;  where  the  interval  is  not  so 
marked,  and  in  contradistinction,  reversible  (Sauveur  suggests 
100°  C.  as  an  arbitrary  limit). 

Commercial  iron  is  never  pure,  and  the  elements  (including 
iron)  of  which  it  is  composed  may  exist  (a)  in  chemical  combina- 
tion, forming  definite  chemical  compounds,  (b)  in  solution  (solid 
solution:  see  below),  where  one  element  or  substance  is  dis- 
solved in  another  in  varying  proportions,  and  (c)  as  mechanical 
mixtures  of  elements  or  compounds.  The  most  important  ele- 
ment to  be  associated  with  iron  is  carbon,  which  has  a  wider 
effect  on  iron  than  any  other,  and  even  when  special  elements 
such  as  nickel,  chrome,  etc.,  are  introduced  its  influence  still 
predominates  or  governs  those  of  the  others.  A  consideration  of 
the  various  relations  between  iron  and  carbon  is  therefore  neces- 
sary, not  only  because  they  are  always  in  evidence,  but  also 
because  it  will  serve  to  explain  the  relations  of  other  elements. 

Determination  of  Critical  Points. — These  may  be  listed  as 
follows : 

(1)  Thermal  or  cooling  and  heating  curve  methods :  Changes  in 
the  ra'tes  of  cooling  or  heating.     Various  methods  of  determina- 
tion have  been  devised  and  also  for  plotting  the  corresponding 
values  of  time  and  temperature. 

(2)  Calorimetric  methods:  Determining  the  amount  of  heat 
evolved  at  different  temperatures. 

(3)  Metallographic  methods :  Examination  of  the  structure 
resulting  by  quenching  from  various  temperatures. 


266  METALLOGRAPHY 

(4)  Thermo-electric  methods:  Changes  in  the  thermo-e.m.f. 
of  the  specimen  and  copper  when  at  different  temperatures. 

(5)  Magnetic   method:    Changes    in    the    thermo-magnetic 
properties. 

(6)  DUatadon  methods:  Changes  in  the  rate  of  expansion  or 
contraction. 

Freezing  and  Solidification. — In  approaching  this  subject  it 
will  be  simpler  to  study  first  the  somewhat  analogous  and  simpler 
case  of  what  happens  when  solutions  containing  different  propor- 
tions of  water  and  common  salt  (NaCl),  varying  from  o  to  100% 
of  each  respectively,  are  cooled  (this  is  the  common  example 
employed,  although  Howe  states  that,  owing  to  certain  com- 
plications, sodium  nitrate  is  better).  If  pure  water  is  cooled  its 
temperature  falls  regularly  until  o°  C.  is  reached,  when  freezing 
occurs  (freezing  point),  the  temperature  remaining  constant 
until  all  the  water  has  frozen,  after  which  the  fall  in  temperature 
again  proceeds  regularly.  If  a  solution  containing  a  small  per- 
centage of  salt,  say  about  2  %  is  cooled,  freezing  does  not  com- 
mence until  a  temperature  below  o°  C.  has  been  reached,  when, 
however,  the  entire  solution  does  not  freeze  as  before.  Instead, 
small  portions  of  nearly  pure  ice  are  gradually  formed  as  the  tem- 
perature is  progressively  reduced,  the  remaining  solution,  in 
consequence,  becoming  richer  and  richer  in  salt.  This  gradual 
separation  of  ice  is  known  as  selective,  progressive  or  differen- 
tial freezing.  Finally  at  —22°  C.  the  temperature  remains 
stationary  until  the  remaining  concentrated  solution  or  mother 
liquor,  which  now  contains  23.6  %  of  salt  has  completely  solidified. 
This  last  freezing  substance  consists,  not  of  crystals  of  salt  dis- 
solved in  ice,  but  of  separate  intimately  mixed,  microscopic 
plates  of  ice  and  salt.  This  mixture  is  termed  a  cryosel,  cryo- 
hydrate  (Guthrie's  cryohydrate),  duplex  constituent,  or  the  more 
general  term,  eutectic  (also  eutectic  mixture  and  eutecticum) . 
The  temperature  at  which  this  occurs  is  termed  the  eutectic 
point,  and  the  line  joining  the  points  for  a  series  of  compositions 
the  eutectic  line;  the  time  occupied  for  such  freezing  is  the 
eutectic  time.  With  a  higher  percentage  of  salt,  say  about 
10  %  cooling  proceeds  to  a  somewhat  lower  temperature  than 
in  the  preceding  case  before  ice  commences  to  separate  out;  but 
the  final  freezing  point  and  the  composition  of  the  mother  liquor 
are  again  —22°  C.  and  23.6%  of  salt,  respectively,  there 
being  of  course  proportionately  more  mother  liquor.  If  the 
solution  contains  exactly  this  percentage  of  salt,  cooling  proceeds 
without  any  separation  of  ice  until  —22°  C.  is  reached,  when 
the  entire  solution  freezes  out  at  this  temperature.  If  more  than 
23.6%  of  salt  is  in  the  original  solution,  then  salt,  instead 
of  ice,  separates  out  initially,  so  that  at  —22°  C.  this  composi- 
tion is  reached.  It  will  thus  be  seen  that  no  matter  what  the 
initial  percentage  of  salt,  the  final  composition  at  —22°  C.  is 
always  the  same.  The  substance  initially  in  excess  of  the  com- 
position of  the  eutectic  (eutectic  ratio)  is  called  the  excess  sub- 
stance; the  other,  the  deficit  substance.  The  mother  liquor, 
when  on  the  point  of  forming  the  eutectic,  is  sometimes  called 


METALLOGRAPHY 


267 


the  eutectic  solution,  and  eutexia  is  the  name  which  has  been 
given  the  act  of  its  formation.  A  curve  for  a  given  composition, 
plotted  to  show  the  rate  of  cooling,  is  termed  a  cooling  curve  or 
sometimes  improperly  recalescence  curve  (the  reverse,  a  heating 
curve);  a  curve  comprising  the  different,  critical  points  for  a 
series  of  different  proportions  of  the  same  constituents  is  known 
as  a  freezing  point  curve  (the  reverse,  a  melting  point  curve). 
Where  a  cooling  solution  solidifies  at  one  temperature  (con- 
gruent freezing,  or  isothermal  freezing),  this  is  termed  the 
freezing  point;  the  isotherm  corresponding  to  this  freezing  point 
is  known  specifically  as  the  tectotherm;  if  differential  freezing 
(incongruent  freezing)  occurs,  the  temperature  at  which  freezing 
commences,  the  upper  freezing  point;  that  at  which  freezing  is 
completed,  the  lower  freezing  point;  and  the  range  of  tempera- 
ture, the  freezing  range. 

Freezing  of  Alloys. — The  same  principles  apply  here  as  in  the 
case  of  the  salt  and  water.  Only  binary  alloys  will  be  discussed 
here.  Those  containing  more  than  two  metals  are  the  same  in 
principle  and  their  additional  complications  require  special 


Molten 


Molten 
Freezing  Point  of  A 

'  -—  _ 
Solid  A  + 

•—-  —  —  4Jquid  B 

Freezi 
So 

ng  Point  of  B 
id  A  and  B 

A-100 
B-  0 


Concentration 


A-    0 
£-100 


Solid  Solution 


A-100 
B-    0 


Concentration 


A-    0 
5-100 


FIG.  32.  FIG.  33. 

FIG.  32. — Constitutional  diagram  for  two  metals  entirely  insoluble 
in  each  other  when  solid. 

FIG.  33. — Constitutional  diagram  for  two  metals  entirely  soluble 
in  each  other  when  cold. 


methods  for  illustration  and  elucidation.  Figs.  32  to  37  inclusive 
show  typical  diagrams  for  different  kinds  of  freezing  and  cooling. 
The  alloy  or  metal,  when  heated  to  a  temperature  where  it  is 
entirely  liquid  is  termed  the  molten.  A  single  metal,  a  definite 
chemical  compound,  and  a  eutectic  each  freeze  completely  at  a 
single  temperature.  In  the  last  two  cases  where  there  is  an  excess 
of  one  of  the  constituents,  or  where  the  alloying  metals  form  solid 
solutions  throughout  their  series,  the  freezing  is  not  isothermal 
but  extends  over  a  range  of  temperature.  Fig.  32  shows  how 
each  of  two  metals  entirely  insoluble  in  each  other  has  its  dis- 
tinct freezing  point  which  is  the  same  as  if  it  alone  were  present. 
In  figures  33  to  37  inclusive  the  curves  show  that,  with  the  excep- 


268 


METALLOGRAPHY 


tions  noted  above,  there  are  two  freezing  point  curves;  the  upper, 
or  liquidus,  where  freezing  commences,  and  the  lower,  or  solidus, 
where  it  is  completed.  In  this  freezing  range  alloys  are  in  the 
mushy  stage  sometimes  spoken  of.  By  careful  cooling  the  alloy 
may  not  freeze  at  a  temperature  below  the  normal  temperature, 


Molten 


Solid  Solution  of    A  +  B 


Molten 


Mother  Meta 


Mother  Metal    Q 


Solidus 
A+Eutectic 


L         Ql        Solidus 


A -100 


Concentration 


A-  0          A  -100        Concentration 
B  -    0  B-100         B  -    0  B-MO 

FIG.  34.  FIG.  35. 

FIG.  34. — Constitutional  diagram  for  two  metals  which  form  solid 
solutions  at  each  end  of  the  series  but  are  partly  insoluble  for  in- 
termediate concentrations. 

FIG.  35. — Constitutional  diagram  for  two  metals  which  form  an 
eutectic  and  are  entirely  insoluble  in  each  other  when  cold. 


Molten 


Solid  \A+% 

3olutioAEutectio° 

of      \ 
A+B  \ 


A-  100 
B-     0 


Solidus 


Concentration 


FIG.  36. 


FIG.  37. 


FIG.  36. — Constitutional  diagram  for  two  metals  partly  eutecti- 
ferous  but  forming  solid  solutions  at  each  end  of  the  series. 

FIG.  37. — Constitutional  diagram  of  two  metals  which  form  a 
definite  chemical  compound  which  is  entirely  soluble  with  either 
metal  when  cold. 

unless  the  condition  is  disturbed  as  by  the  introduction  of  a  crys- 
tal of -^  the  alloy  (inoculation);  this  is  known  as  undercooling, 
surfusion  or  superfusion.  This  is  due  to  lag  or  a  condition  of 
internal  friction  or  molecular  friction,  also  called  molecular 


METALLOGRAPHY  269 

inertia  or  hysteresis  (see  Phase  Rule,  page  327);  where  this  does 
not  occur  during  a  change  of  state  or  condition,  the  change  is  said 
to  be  lagless.  If  cooled  still  further,  freezing  takes  place  spon- 
taneously (spontaneous  crystallization)  when  any  disturbance, 
such  as  jarring,  occurs.  These  two  ranges  have  been  named  by 
Ostwald  metastable  range  and  labile  range  respectively.  The 
molecular  inertia  which  prevents,  or  tends  to  prevent  freezing  at 
the  normal  temperature,  acts  in  accordance  with  what  is  some- 
times termed  the  law  of  passive  resistance.  "Below  the  solu- 
bility curve,  and  approximately  parallel  with  it,  lies  a  curve 
representing  the  temperature  at  which  each  solution  begins  to 
deposit  spontaneously  without  inoculation  with  a  crystal.  To 
this  curve  the  name  supersolubility  curve  has  been  given.  The 
intersection  of  two  supersolubility  curves  is  called  the  hyper- 
tectic  point,  corresponding  to  eutectic  point"  (Desch).  Sub- 
stances separating  before  the  eutectic  forms  are  called 
pro-eutectic ;  if  after  the  eutectic,  post-eutectic.  Depending  upon 
its  structure  the  eutectic  may  be  lamellar  or  granular.  To  illus- 
trate how  these  diagrams  are  used  consider  what  takes  place  in 
cooling  an  alloy  whose  temperature  and  concentration  are  repre- 
sented by  the  point  R  in  Figs.  33  and  35.  Here  there  is  molten 
solution,  and 'no  change  in  constitution  occurs  until  /  is  reached, 
when  the  alloy  begins  to  freeze.  The  point  M  on  the  solidus  curve 
indicates  the  composition  of  these  crystals;  as  the  temperature 
falls  the  molten  becomes  progressively  richer  in  A  metal,  follow- 
ing the  liquidus  curve,  and  the  crystals  correspondingly  poorer, 
following  the  solidus  curve,  so  that  when  the  L  is  reached  for  the 
molten,  the  crystals  have  the  concentration  shown  by  O.  The 
intercepts  JM  and  LO  on  the  isothermal  abscissae  represent  in 
each  case  100%  of  molten  plus  crystals;  for  JM  there  is  100% 
molten  and  o%  crystals;  for  LO  the  reverse  is  the  case.  If  any 
point  P  is  selected  within  the  liquidus  and  the  solidus  curve  the 
abscissae  passing  through  it  intersects  them  respectively  at  K 
and  N  which  indicate  the  concentration  for  each;  the  amount  of 

PN 

each  is  found  by  the  ratio  between  PK  and  PN,  thus  -^^  X  100  = 

rl\. 

PK 
%K,  and  j^  X  100  =  %N.    In  the  case  of  the  cooling  of  the 

alloy  which  forms  the  solid  solution  the  original  heterogeneity  of 
the  crystals  is  overcome  by  diffusion  unless  the  cooling  is  unduly 
rapid;  this  is  not  so  complete  with  subsequent  transformations  in 
solid  solutions  owing  to  the  greater  viscosity.  With  eutectics 
there  persists  the  simultaneous  existence  of  eutectic  and  excess 
substance;  the  same  also  in  the  case  of  eutectoids  formed  in  solid 
solutions. 

As  ordinarily  understood  a  solution  is  something  which  is  liquid 
at  or  near  atmospheric  temperatures,  whereas  a  molten  substance 
connotes  very  much  higher  temperatures.  The  question  is, 
therefore,  really  one  of  degree  only,  and  what  is  true  of  an  ordinary 
solution  is  also  relatively  true  of  one  which  is  molten.  The 
term  molten  or  melt  is  accordingly  used  to  designate  this  case 
in  contradistinction  to  solid  (at  lower  or  ordinary  temperatures). 


270  METALLOGRAPHY 

Where  a  molten  solution  solidifies  with  differential  freezing,  the 
upper  freezing  point  (also  the  curve  for  a  series  of  different  com- 
positions) is  termed  the  liquidus  (also  liquidus  curve),  the  lower 
point  and  curve,  the  solidus  (also  solidus  curve),  and  the  freezing 
range,  the  solidification  range.  Where  a  eutectic  (eutectic 
mixture,  eutectic  alloy)  is  formed,  the  metal  just  before  final 
solidification  is  called  the  mother  metal. 

Metallic  Solid  Solution. — It  may  at  first  be  somewhat  diffi- 
cult to  grasp  the  idea  of  changes  occurring  in  solid  material,  but  a 
little  thought  will  show  that  the  principal  difference  between  a 
solid,  such  as  a  metal,  and  a  liquid,  is  in  the  degree  of  mobility  of 
the  particles  or  molecules,  as  no  sharp  division  can  be  drawn. 
From  naphtha  or  alcohol,  for  example,  as  one  extreme,  whose  par- 
ticles are  highly  mobile,  to  a  heavy  oil,  to  molasses,  to  lead,  to 
highly  heated  steel,  and  finally  to  the  same  metal  when  cold 
(which  can  still  flow  to  a  considerable  extent,  as  in  the  case  of 
wire  drawing)  as  the  other  extreme,  the  steps  are  relatively  grad- 
ual. We  therefore  properly  speak  of  a  solid  solution,  in  which 
the  degree  of  viscosity  is  high,  as  similar  to  a  liquid  solution  (in 
contradistinction),  such  as  the  salt  solution  already  discussed,  in 
which  the  particles  have  greater  freedom  of  movement.  A  solid 
solution,  also  termed  isomorphous  mixture  or  mixed  crystals 
(according  to  Professor  Howe),  "is  a  solid  having  the  essential 
properties  which  characterize  liquid  solutions  as  distinguished 
from  chemical  compounds.  These  characteristics  are  twofold: 
(i)  a  solution  resembles  a  definite  chemical  compound  in  that  its 
components  completely  lose  their  identity  and  become  integrated 
to  form  a  new  substance;  (2)  solutions  differ  from  definite  chem- 
ical compounds  in  that  their  components  unite,  not  in  definite  but 
in  intermediate  proportions,  which  vary  by  infinitesimal  grada- 
tions from  specimen  to  specimen.  The  variations  in  composi- 
tion between  definite  chemical  compounds  are  per  saltum,  those 
between  solutions  are  per  gradum.  The  properties  of  solutions, 
both  liquid  and  solid,  habitually  differ  much  less  from  the  mean 
of  those  of  their  components  than  from  the  properties  of  definite 
chemical  compounds."  A  solidified  solution  or  congealed 
solution  is  a  "homogeneous  solution  after  solidification,  irre-v 
spective  of  whether  the  constituents  of  the  solution  in  the  latter 
siate  form  a  mixture  or  a  solid  solution  in  the  true  sense  of  the 
term"  (I.  A.  T.  M.).  Metallic  solid  solutions,  from  their 
structure,  are  sometimes  referred  to  as  crystalline  solid  solutions. 

For  solid  solutions  the  term  eutectoid  (of  the  nature  of  or 
resembling  a  eutectic)  has  now  been  generally  adopted,  although 
"eutectic"  is  still  sometimes  met  with  for  this  particular  case; 
the  terms  aeolic  or  benmutic  were  suggested  but  have  never 
come  into  use.  The  terms  eutropic  mixture  and  eutropic  point 
(Rinne)  were  proposed  to  distinguish  changes  going  on  during 
cooling  after  solidification  from  the  eutectic  changes  during  solidi- 
fication itself.  To  indicate  the  similar  changes  leading  up  to  the 
formation  of  the  eutectoid  the  upper  point  (and  curve)  is  known 
as  the  liquidoid  and  the  lower  the  solidoid. 

Cooling  of  Solid  Solutions.— As  illustrated  by  the  iron-carbon 


METALLOGRAPHY 


271 


diagram  (Fig.  38),  changes,  known  as  transformations,  inversions, 
thermal  metamorphisms,  or  transitions  occur  similar  to  those  on 
freezing,  giving  rise  to  what  are  termed  transformation  curves. 
Where  there  is  a  eutectoid,  formed  by  the  excess  substance  being 
expelled  from  the  solid  solution,  there  is  a  selective  transfor- 
mation; constituents  formed  before  the  eutectoid  are  called 
pro-eutectoid,  those  afterward,  post-eutectoid ;  in  the  case  of 
iron-carbon  alloys  the  latter  is  also  referred  to  as  the  pearlite  or 
sub -transformation  range. 

Iron-Carbon  Diagrams.— These  are  also  referred  to  as  equi- 
librium, state,  or  constitutional  diagrams  because  they  serve  to 
illustrate  what  "states  are  normal  under  different  conditions  of 
temperature  and  concentration  (composition).  Howe  (Metallog. 
of  Steel)  points  out  that  such  a  diagram  is  made  up  of  two  parts : 


1 

Molten  Jron 

2        ^*\>>^  ( Fer  Fondu ) 

Molten  Iron 

(Fer  Fondu) 

Austenite 


Anstenite  + Cementite 


Cementite 

+ 
Pearlite 


01  2345 

Carbon  Per  Cent 

FIG.  38. — Constitutional  diagram  for  iron-carbon  alloys. 
(I.A.T.  M.) 

an  underscored  V  for  the  eutectic  portion  and  another  under- 
scored V  for  the  eutectoid  portion.  This  forms  a  basis  for  one 
classification  of  iron-carbon  alloys:  with  4.30%  carbon  there  is 
eutectic  cast  iron;  with  more  carbon,  hyper-eutectic  cast  iron; 
with  less  carbon,  hypo-eutectic  steel  and  cast  iron.  Considering 
the  lower  V,  with  carbon  about  0.85%  there  is  eutectoid  steel; 
when  the  carbon  is  greater,  hyper-eutectoid  steel;  and  if  less, 
hypo-eutectoid  steel  (this  also  applies  to  the  matrix  of  cast  iron, 
i.e.,  exclusive  of  any  graphite).  As  cementite  is  metastable 
while  graphite  is  stable,  there  are  two  forms  of  diagrams,  (a)  the 
iron-cementite  or  metastable  diagram,  and  (ft)  the  iron-graphite 
or  stable  diagram.  In  Fig.  38  is  shown  the  iron-cementite  dia- 
gram appearing  in  the  report  of  Committee  53  of  the  Inter- 
national Association  for  Testing  Materials  (I.  A.  T.  M.  diagram). 
Various  diagrams  have  been  gotten  up  by  the  following:  Iron- 


272  METALLOGRAPHY 

carbon— Benedicks  (Sauveur,  Metallography,  446),  Carpenter  and 
Keeling  (ibid.,  445),  Gutowsky,  Mannesmann  (considered  by 
Howe  to  be  the  earliest),  Rosenhain  (Sauveur,  447),  Ruff  (ibid., 
449),  Roozeboom  (ibid.,  444),  Roberts -Austen  (ibid.,  442-3), 
Sauveur  (ibid.,  441),  Wittorff  (ibid.,  450),  Upton  (ibid.,  448);  iron- 
phosphorus— Desch  (/.  /.  &  S.,  1915, 1,  195),  Konstantinoff 
(ibid.,  194),  Saklarwalla  (ibid.,  193). 

Constituents  of  Iron  Alloys. — i.  Ferrite  (Howe):  first  used  for 
pure  iron,  now  employed  to  designate  that  part  of  iron  or  steel 
containing  no  carbon  (or  only  a  trace)  in  solid  solution.  It  has 
been  suggested  by  Stead  that  ferrite  when  consisting  of  practi- 
cally pure  iron  should  be  called  ferro -ferrite.  When  the  iron  is 
associated  with  considerable  quantities  of  substances  with  which 
it  forms  solutions  or  isomorphous  mixtures,  such  as  phosphide  of 
iron,  or  nickel,  aluminum,  manganese,  silicon,  chromium,  vana- 
dium, etc.,  they  should  be  called  respectively  phospho-ferrite, 
nickel-ferrite,  alumino-ferrite,  mangano-ferrite,  silico -ferrite, 
chromo-ferrite,  vanado-ferrite,  etc.  (i)  alpha  (a)  iron  is  pure 
iron  in  its  normal  condition  below  Ar2  (750°  C.,  1382°  F.).  It 
crystallizes  in  the  cubic  (isometric)  system;  is  strongly  magnetic 
(I.  A.  T.  M.).  It  cannot  dissolve  carbon  or  only  to  a  very  limited 
extent.  (2)  Beta  (/3)  iron,  according  to  Osmond,  is  an  allotropic, 
non-magnetic  variety  of  pure  iron,  existing  at  temperatures 
between  Ar2  (750°  C.,  1382°  F.)  and  Ar,  (860°  C.,  1580°  F.).  It  is 
isomorphous  with  alpha  iron,  crystallizing  in  the  cubic  system. 
When  beta  iron  changes  to  alpha  iron,  heat  is  evolved  and  mag- 
netic properties  are  developed.  The  term  was  formerly  applied 
to  iron  at  all  temperatures  above  Ar2  (I.  A.  T.  M.).  It  has  the 
property  of  dissolving  carbon  to  a  limited  extent.  Gamma  (7) 
iron,  according  to  Osmond,  is  an  allotropic,  non-magnetic  variety 
of  pure  iron  existing  at  temperatures  above  Ar^  (860°  C.,  1580°  F.). 
It  crystallizes  in  the  cubic  system,  and  in  crystalline  forms  of  the 
cube  and  the  octahedron  (but  more  frequently  of  the  octahedron) 
derived  from  the  cube.  In  passing  from  the  state  of  gamma  iron 
to  that  of  beta  iron  an  evolution  of  heat  occurs  (I.  A.  T.  M.).  A 
fourth  allotropic  modification,  delta  (5)  iron  was  claimed  by  New- 
all  in  1887  and  Tomlinson  in  1888.  The  transformation  point 
was  supposed  to  occur  at  about  1000°  C.  Recenty  G.  Rumelin 
and  K.  Fick  (Ferrum,  also  /.  /.  &°  S.  /.,  1915, 1,  622)  state  that,  in 
investigating  the  iron-manganese  system,  they  have  detected 
the  5-7  transformation.  Free  iron  was  the  term  proposed  by 
Sorby.  The  ferrite  contained  in  pearlite  is  referred  to  as  pearlitic 
ferrite,  eutectoid  ferrite,  or  pearlite  ferrite;  when  not  so  com- 
bined, free  ferrite,  massive  ferrite,  excess  ferrite,  surplus  ferrite, 
non-eutectoid  ferrite,  structurally  free  ferrite;  what  separates 
out  before  pearlite  is  formed,  pro -eutectoid  ferrite.  Total  ferrite 
refers  to  all  the  ferrite  present  both  free  and  associated. 

2.  Cementite  (Howe):  a  carbide  of  iron  having  the  formula 
Fe3C.  It  (and  the  form  of  carbon)  is  also  termed  Abel's  carbide 
of  iron,  carbon  of  normal  carbide  (Ledebur),  reheated  carbon 
(Osmond  and  Werth),  carbon  of  cementation  (Caron),  cementa- 
tion carbon,  cement  carbon,  carbon  of  annealing,  normal  carbide, 


METALLOGRAPHY  273 

carbide  carbon,  cementite  carbide.  Cementite  may  exist  in  fine 
granules,  thin  plates,  or  in  comparatively  large  masses  in  steel  and 
pig  iron.  According  to  Osmond  it  is  the  hardest  constituent  in 
metal  and  steel,  not  colorable  by  polishing  and  etching  with 
various  reagents  (except  sodium  picrate — see  Etching  below). 
Sauveur  distinguishes  segregated  cementite  and  free  cementite 
(also  called  non-eutectic  cementite,  surplus  carbide,  massive 
cementite) :  the  former  is  a  constituent  of  pearlite  while  the  lat- 
ter occurs  independently.  As  the  etrm  "segregated"  suggests 
separation,  and  as  one  authority  has  called  free  cementite  "segre- 
gated," it  appears  advisable  to  substitute  the  term  pearlite- 
cementite  (I.  A.  T.  M.),  pearlitic  cementite  or  eutectoid  cemen- 
tite, free  cementite  is  also  called  non-eutectoid  cementite, 
structurally  free  cementite  or  excess  cementite.  The  cementite 
in  the  eutectic  (when  it  freezes)  is  called  eutectic  cementite.  Howe 
suggests  for  the  cementite  which  separates  before  the  eutectic  is 
formed,  the  terms  pro-eutectic  or  primary  cementite,  and  as  an 
analogy  for  the  cementite  which  may  separate  before  the  eutec- 
toid, the  term  pro-eutectoid  cement.  Sauveur  suggests  the 
terms  alpha  cementite  for  the  variety  insoluble  in  iron,  and 
gamma  cementite  when  it  is  soluble;  this  latter  variety  has  also 
been  called  regular  cementite  or  solvite.  Total  cementite  refers 
to  all  that  may  be  present,  both  free  and  associated. 

3.  Pearlite  (Howe). — A  eutectoid  of  cementite  and  crystal- 
lized iron  formed  by  slow  cooling  past  Ar\.  Also  called  pearly 
constituent  (Sorby),  pearlyte  (Howe),  perlite  (Osmond),  cryo- 
carbide  (Arnold).  When  pure  it  contains  approximately  0.89% 
Varbon.  Steel  containing  about  this  percentage  of  carbon 
(known  as  the  structural  saturation  point),  is  called  eutectoid 
steel,  aeolic  steel,  benmutic  steel,  eutectic  steel,  and  saturated 
steel;  if  more  than  this,  hyper-eutectoid,  hyper-aeolic,  hyper- 
eutectic,  or  supersaturated;  if  less  than  this,  hypo -eutectoid, 
hypo-aeolic,  hypo -eutectic,  or  unsaturated.  It  consists  of  alter- 
nating plates  of  cementite  and  ferrite  or  possibly  sorbite  (see 
below),  or  grains  of  cementite  embedded  in  ferrite  or  possibly 
sorbite  ([.  A.  T.  M.).  Normally  pearlite  should  consist  of  6.4 
parts  of  ferrite  to  i  part  of  cementite  (by  weight),  but  it  should 
be  regarded,  however,  as  a  variable  mixture,  for  in  structuaal 
steels  containing  between  0.5  and  1.0%  manganese,  the  carbon 
in  pearlite  varies  between  0.6  and  0.9%,  and  in  some  tool  steels, 
according  to  the  method  of  treatment,  the  pearlite,  accompanied 
by  free  cementite,  may  contain  i%  carbon  (Stead).  The  range 
of  temperature  throughout  which  pearlite  can  form  is  known  as 
the  pearlitic  range.  A\  is  essentially  a  pearlite  point  while  the 
upper  limits  of  hypo-eutectoid  steel  are  ferrite  poults  and  the 
upper  limit  of  hyper-eutectoid  steel  is  a  cementite  point.  The 
structure  of  pearlite  depends  upon  the  nature  of  the  cooling 
which  it  has  undergone.  If  the  cooling  is  rapid  the  structure  loses 
distinctness  and  is  called  by  Arnold  sorbitic  pearlite  (usually 
considered  as  sorbite,  see  below) ;  with  slower  cooling  the  struc- 
ture is  distinct  and  is  termed  true  pearlite  or  by  Arnold,  normal; 
with  still  slower  cooling  the  structure  is  coarsened  and  is  known 
18 


274 


METALLOGRAPHY 


as  laminated  pearlite.  If  the  temperature  is  held  for  some  time 
just  below  the  lower  critical,  the  two  constituents  tend  to  sepa- 
rate into  globules,  kn&wn  as  spheroidizing  or  divorcing  (divorcing 
annealing)  (Howe)  and  the  structure  is  termed  globular,  granu- 
lar or  beaded  pearlite  (Benedicks).  In  examining  a  piece  of 
native  iron,  Benedicks  discovered  a  structure  which  he  classed 
as  a  new  micrographic  constituent  and  named  oxide  pearlite. 

4.  Austenite  (Howe). — The  following  definitions  are  suggested 
by  H.  M.  Howe  (T.  A.I.  M.  E.,  XXIX  (1908),  4-7)-:  (a)  Gener- 
ically,  the  solid  solution  of  iron  carbide  in  iron,  stable,  for 


STEEL 


1500 


AUSTENITE  +  CfMENTITE 
Pro-eutectoid  Cementite  farms  progressively 


Ar2  i     Austenite  here  splits  up  into  Pearlite  =  eutectold 
rerrlte  and  cementite 


CARBON  0       0.5      1.0      1.5      2.0     2.5      3.0      8.5      4.0      4.5      5.0      5^      6.0     630.91 
WON     100     99.5     99.0     98.5     98.0    97.5     97.0    96.5     96.0     95.5    95.0     94.5    ,94.0    S3.5  93.33 
PERCENTAGE  COMPOSITION 

PIG.  39. — The  carbon-iron  diagram.      (Howe.) 

instance,  above  the  transformation  range  AI  to  A3.  (b)  Specific- 
ally, this  same  solid  solution  as  preserved  in  the  cold,  more  or  less 
decomposed,  for  instance,  by  quenching  steel  containing  more 
than  1.5%  of  carbon  from  above  1100°  C.  in  ice  water.  When 
the  structure  of  such  steel  is  developed  by  polishing  on  parch- 
ment moistened  with  licorice  solution  or  ammonium  nitrate  after 
reheating  to  200°  C.,  or  by  etching  with  hydrochloric  acid  in  an 
electric  current,  the  austenite  remains  white  while  the  zigzag 
martensite  with  which  it  is  often  associated  becomes  brown. 
Primary  austenite,  that  which  separates  from  the  molten  metal  in 
cooling  through  region  2  of  Fig.  39.  Primary  cementite,  that 


METALLOGRAPHY  275 

which  separates  from  the  molten  metal  in  cooling  through  region 
3.  Eutectic  austenite,  that  which  forms  on  crossing  the  bound- 
ary aBc  in  cooling  from  region  2  or  3  into  region  7,  and  forms  part 
of  the  eutectic.  Eutectic  cementite,  that  which  forms  on  cross- 
ing the  boundary  aBc  from  region  2  or  3  into  region  7,  and  forms 
part  of  the  eutectic.  Pro-eutectic  ferrite,  that  which  forms  from 
the  austenite  in  cooling  through  region  5.  It  is  the  same  as 
excess  ferrite.  Pro-eutectic  cementite,  that  which  forms  in  the 
austenite  in  cooling  through  region  7,  and  therefore  immediately 
precedes  the  eutectoid  cementite,  i.  e.,  that  of  the  pearlite  formed 
on  cooling  past  Ar\.  Primaustenoid,  the  network,  spines,  and 
other  masses  rich  in  ferrite  and  therefore  poor  in  carbon  which  in 
hypo-eutectoid  steel  persist  in  undiffused  relics  of  the  primary 
austenite  formed  in  cooling  through  region  2.  So  long  as  they 
persist,  the  heat  treatment  or  the  mechanical  work  which  the 
metal  has  undergone  cannot  be  considered  as  complete,  though  it 
may  be  sufficient  for  many  purposes.  Primaustenal,  adj.,  of  or 
relating  to  primaustenoid.  (For  the  above  Howe  claims  no  origi- 
nality. He  says  the  second  to  fifth  are  already  in  use  in  the  pres- 
ent or  a  similar  form;  he  thinks  the  remainder  distinctly  new.) 
The  pro-eutectic  ferrite  is  clearly  that  which  Professor  Sauveur 
has  called  structurally  free  ferrite.  Howe  has  hitherto  called  it 
excess  ferrite.  The  primary,  eutectic,  and  pro-eutectoid  cemen- 
tite jointly  form  what  Professor  Sauveur  has  called  struc- 
turally free  cementite,  and  Howe  has  hitherto  called  excess 
cementite.  Indeed,  it  is  the  need  of  subdividing  this  excess 
cementite  and  assigning  a  specific  name,  pro-eutectoid,  to  that 
which  separates  in  cooling  through  region  7  that  has  led  (him)  to 
propose  the  name  pro-eutectoid  ferrite  instead  of  excess  ferrite. 
The  former  has  the  merit  not  only  of  matching  the  corresponding 
cementite  but  of  indicating  the  genesis.  The  eutectoid  ferrite 
and  cementite  are  clearly  those  which  result  from  the  splitting 
up  of  the  hardenite  and  are  habitually  interstratified  as  pearlite. 
The  carbon  dissolved  in  the  austenite,  and  exclusive  of  any  in  the 
form  of  cementite,  has  been  termed  dissolved  carbon. 

Austenite  is  sometimes  called  mixed  crystals,  gamma  iron,  and 
(wrongly)  martensite.  Primary  austenite  is  also  referred  to  as 
pro-eutectic.  Primaustenoid  is  also  called  simply  austenoid  or 
eutectic  austenoid  and  saturated  austenoid  to  indicate  a  content 
of  1.70%  C.  Hardenite  is  the  name  given  to  austenite  of  eutec- 
toid composition  (0.9  %  carbon),  formerly  classed  as  a  special  case 
of  martensite.  Arnold  and  Read  have  shown  that  there  are  four 
hardenites:  iron  hardenite  (Fe2iFe3C),  vanadium  hardenite 
(Fe72V4C3),  tungsten  hardenite  (Fe2eWC),  ferro-molybdenum 
hardenite  (Fe24Fe3Mo3C).  Edwards  interpreted  the  term  ther- 
mal stability  to  mean  the  power  which  the  hardenites  possess  of 
resisting  the  softening  action  of  heat  when  they  are  heated  to 
different  temperatures.  The  range  in  temperature  at  which 
austenite  exists  in  known  as  the  austenite  range.  The  trans- 
formation of  hypo-eutectoid  steel  consists  of  two  parts,  the 
selective  part  and  the  eutectoid  part  called  also  the  austenite  - 
pearlite  inversion  or  recalescence  (Howe).  A  steel  (usually  cer- 


276  METALLOGRAPHY 

tain  types  of  alloy  steel)  which  contains  austenite  is  described  as 
austenitic;  where  free  cementite  is  present,  it  has  been  called 
cementito-austenitic ;  if  martensite  is  also  present,  austenito- 
martensitic. 

5.  Martensite  (Osmond). — A  transition  form  between  austenite 
on  the  one  hand  and  ferrite  and  cementite  on  the  other,  prob- 
ably containing  all  three  of  these  substances,  but  in  varying  pro- 
portions (Howe).     It  contains  varying  amounts  of  carbon  up  to 
about  i. 80%.     The  term  hardenite  was  at  one  time  used  by 
Howe  for  martensite  of  eutectoid  composition  (0.89%  carbon), 
and  it  was  also  employed  for  saturated  martensite  with  1.80% 
carbon.     It  is  harder  than  austenite  and  according  to  Osmond  its 
hardness  is  probably  due  to  its  containing  beta  iron.     It  is 
magnetic;  upon  polishing,  etching,  and  examining  under  the 
microscope  it  has  usually  a  characteristic  structure  of  intersect- 
ing needles  parallel  to  the  three  sides  of  a  triangle  (acicular  mar- 
tensite).    Howe  and  Levy  found  by  certain  treatments  marten- 
site  resulted  without  this  structure  and  suggested,  provisionally, 
the  term  emulsion  martensite  (non-acicular  martensite),  and 
where  a  banded  structure  resulted,  lamellar  martensite.    Gamma 
martensite  is  the  name  sometimes  given  to  the  form  existing  only 
above  Ar\.     It  contains  carbon  dissolved  in  gamma,  and  prob- 
ably also  beta  (Osmond)  iron,  this  form  of  carbon  being  called 
hardening  carbon,  hardening  carbide,  and  martensite  carbon.    It 
is  obtained  by  rapid  cooling  from  the  austenite  state  or  by  ordi- 
nary cooling  with  certain  elements  present  which  promote  lag 
(obstructive  elements)  such  as  nickel,  manganese,  etc.     This 
change  to  martensite  has  been  termed  by  Howe  martensitization. 
According  to  Kroll  martensite  may  be  simultaneously  osmoditic, 
troostitic,  or  tempering. 

6.  Troostite. — A    transition    form    between    austenite,    and 
cementite  and  ferrite,  occurring  while  cooling  through  Arz.     It 
may  be  obtained  by  quenching  while  cooling  through  this  point, 
and  also  by  reheating  martensite  at  a  low  temperature  consider- 
ably below  Ar\.     Upon  polishing,  etching,  and  examining  under 
the  microscope,  it  appears  as  dark  colored  masses  somewhat 
resembling  in  form  peanuts  or  links  of  sausages.     Kroll  considers 
it  as  deposited  solvite  more  or  less  saturated  with  gamma  iron 
attached.     It  has  been  called  by  Arnold  emulsified  pearlite  or 
emulsified  carbide. 

7.  Sorbite. — A  transition  form  between  troostite  and  pearlite, 
occurring  while  cooling  through  Ar\.     It  may  be  obtained  by 
quenching  while  cooling  through  this  point  and  also  by  reheating 
to  a  temperature  a  little  above  that  for  troostite  but  considerably 
below  what  is  necessary  for  the  formation  of  pearlite.     Upon 
polishing,    etching,    and   examining   under   the   microscope,   it 
appears  as  a  brownish  colored  constituent  looking  like  blurred 
pearlite,  and  for  this  reason  has  been  called  unsegregated  pearl- 
ite.    It  has  been  referred  to  by  Arnold  and  Read  as  "pearlite 
containing  very  finely  granulated  carbide."     Sauveur  says  it  is 
now  generally  regarded  as  an  uncoagulated  mixture  of  the  con- 
stituents of  troostite  and  pearlite.     It  apparently  contains  (i) 


METALLOGRAPHY  277 

some  hardening  carbon,  that  is,  carbon  or  carbide  of  iron  dissolved 
in  beta  iron,  (2)  a  considerable  quantity  of  alpha  iron,  and  (3) 
a  considerable  quantity  of  crystallized  carbide  of  iron  (cement 
carbon).  Howe  terms  sorbitism  the  condition  when  material 
has  a  sorbitic  structure,  i.e.,  structural  fineness,  caused  by 
restraining  the  natural  tendency  of  the  structural  components  to 
coalesce  into  larger  and  larger  masses  (pearlite),  with  progressive 
deterioration  of  the  quality. 

8.  Troosto-sorbite  (Kourbatoff). — This  is  troostite  which  has 
not  undergone  as  much  transformation  as  sorbite,  but  there  is  no 
sharp  line  of  demarkation. 

9.  Osmondite  (Heyn). — Another  homogeneous  phase  or  transi- 
tion product  between  troostite  and  sorbite  closely  related  to  the 
preceding.     It  is  essentially  iron  in  a  stressed  condition  (from 
rapid  cooling),  with  carbon  in  the  form  of  hardening  carbon.     It 
is  also  formed  by  reheating  quenched  material  to  about  400°  C. 
and  is  the  condition  in  which  iron  is  most  soluble  in  dilute  acids. 
Benedicks'  colloid  hypothesis  is  that  osmondite  is  a  colloidal 
solution  of  carbide  of  iron. 

10.  Steadite   (Sauveur). — In  suggesting  this  name  Sauveur 
states  that  Stead  writes  that  in  very  gray  phosphoretic  metals  the 
carbon  diffuses  out  of  it  and  a  binary  eutectic  of  FesP  and  Fe  con- 
taining in  solution  a  little  phosphorus  is  formed.     Steadite,  the 
binary  eutectic,  according  to  Stead,  contains  about  10%  (10.2%) 
P  and  90%  (89.8%)  Fe. 

1 1.  Ferronite  (Benedicks) . — "  Benedicks,  for  instance,  believes, 
or  at  least  believed  at  one  time,  that  the  pearlite  ferrite  of  some 
steels  could  contain  as  much  as  0.27%  carbon  dissolved  in  beta 
iron,  whereas  free  ferrite  is  in  the  alpha  condition.     This  car- 
burized  and  allotropic  ferrite  Benedicks  calls  ferronite"  (Sau- 
veur).    Guillet  says  that  with  steels  under  0.27%  carbon,  the 
ferrite  may  contain  about  0.17%  carbon  as  uncolored  patches  in 
the  pearlite. 

12.  Arnoldite  (Stead). — "If  Dr.  Arnold  had  not  shown  him- 
self so  very  averse  to  having  people's  names  introduced  into 
nomenclature  he  would  have  suggested  that  vanadium  steels 
ought  to  be  called  arnoldite  steels,  because  really  their  wonder- 
ful properties  were  first  brought  out  and  described  by  Professor 
Arnold"  (Stead). 

13.  Ledeburite   (Wiist). — The  eutectic  which  cementite  forms 
with  part  of  the  austenoid  aggregate  and  is  comparable  with 
pearlite.     It  contains  52  parts  by  weight  of  cementite  to  48  parts 
of  1.70%  austenoid  (Howe).     Bauer  and  Deiss  describe  it  as  the 
mixed  crystals  (austenoid) — cementite  eutectic  with  4.2  %  carbon, 
formed  at  a  temperature  of  about  1130°  C.     It  is  produced  by  the 
rapid  cooling  of  white  cast  iron  during  or  just  below  the  point  of 
solidification.     Alcoholic  hydrochloric  acid  attacks  the  plates 
of  mixed  crystals  (with  about  1.76%  carbon)  the  same  as  marten- 
site;  the  cementite  plates  are  not  attacked. 

14.  Graphite. — Nearly  pure  carbon  occurring  in  thin  curved 
plates  and  always  amorphous.     Graphite  is  the  stable  form  of 
carbon  and  the  carbide  (cementite)  is  the  metastable  form;  cer- 


278  METALLOGRAPHY 

tain  conditions  such  as  slow  or  prolonged  heating  or  the  presence 
of  certain  elements,  especially  silicon,  tend  to  produce  the  reac- 
tion Fe3C  =  3Fe  +  graphite,  known  as  graphitization  of  cemen- 
tite.  A  variety  produced  in  malleable  castings  is  called  temper 
carbon  or  annealing  carbon.  As  opposed  to  this  graphitic  carbon, 
Howe  has  proposed  the  term  agraphitic  carbon:  that  commonly 
known  as  combined  carbon,  including  both  that  dissolved  in  aus- 
tenite  and  any  present  in  cementite. 

It  may  be  repeated  that  the  condition  of  carbon  is  (i)  in  solu- 
tion above  AI  (or  Aei)  as  hardening  carbon,  and  (2)  below 
this  point  as  cement  carbon,  or  (3)  in  both  cases  in  the  free  state 
as  graphite.  In  1906  Sauveur  expressed  the  opinion  (Sauveur's 
hypothesis  of  the  allotropic  transformations  and  of  the  dissolving 
power  of  iron  for  carbon)  that  it  was  far  from  certain  that  the 
liberation  of  iron  from  solution  must  precede,  or  at  least  be  simul- 
taneous with,  the  allotropic  changes  affecting  the  iron  at  certain 
critical  temperatures.  The  hypothesis  was  advanced  that  in 
solution  it  might  first  undergo  an  allotropic  modification  and  then 
be  expelled  in  its  new  allotropic  form.  It  is  evident  that  if  the 
allotropic  transformation  of  iron  from  the  gamma  to  the  beta 
and  then  to  the  alpha  state  precedes  its  liberation  from  solution, 
three  solid  solutions  of  carbon  in  iron  are  formed  during  cooling, 
namely,  carbon  (or  Fe3C)  dissolved  (i)  in  gamma  iron,  (2)  in 
beta  iron,  and  (3)  in  alpha  iron.  The  first  solid  solution  is 
universally  called  austenite,  while  this  hypothesis  leads  almost 
irresistibly  to  regarding  the  solid  solution  in  beta  iron  as  marten- 
site  and  the  solid  solution  in  alpha  iron  as  troostite  (Sauveur). 

"G.  Auchy  (Iron  Age,  1915,  XCV,  50-51)  propounds  a  chemical 
theory  to  explain  the  different  properties  of  iron-carbon  steels  on 
the  assumption  of  the  existence  of  ferrated  carbides  (compounds 
of  iron  and  carbide  of -iron).  The  carbides,  which  it  is  suggested 
are  factors  in  the  problem,  are:  cementite;  the  austenites  (fer- 
rated Fe2C  compounds);  the  martensites  (similar  compounds); 
and  hardite  (a  ferrated  Fe-C  compound).  According  to  the 
chemical  theory  set  forth  the  white -etching  constituent  of  hyper- 
eutectoid  steels  is  never  hard  cementite  (FesC)  but  always  soft 
austenite,  and  the  white-etching  constituent  of  hypo -steels 
above  0.22%  of  carbon,  never  ferrite,  but  austenite.  In  cast 
iron,  hardite  is  an  intensely  hard,  unstable,  white-etching  per- 
carbide  FeC-5Fe,  containing  3.45%  carbon,  formed,  if  the 
cooling  be  rapid,  at  about  1200°  C.  by  the  reaction  of  1.76  carbon- 
austenite  upon  6.67  carbon-austenite-cementite.  As  a  matter  of 
fact,  the  theory  that  austenites,  martensites,  and  hardite  are 
definitely  ferrated  chemical  compounds  need  not  be  insisted  on, 
and  they  might  be  regarded  as  solid  solutions  in  indefinite  pro- 
portions of  FesC,  Fe2C,  and  FeC  respectively  in  iron.  At  best, 
the  difficulty  may  be  met  by  assuming  definite  ferration  at  solidi- 
fication'^/. /.  &  S.  L,  1915,11,317-8).  To  distinguish  between 
cementite  which  is  nearly  insoluble  in  dilute  sulphuric  acid,  and 
the  soluble  form  of  carbon  found  in  osmondite  and  troostite, 
Heyn  suggested  the  latter  be  designated  by  the  symbol  Cf. 
Miscellaneous  Constituents. — Following  is  a  list  of  the  princi- 


METALLOGRAPHY  279 

pal  constituents  occurring  in  some  cases  as  impurities  or  what 
Hibbard  calls  sonims:  "A  solid  non-metallic  portion  of  matter 
existing  as  an  impurity  in  metal.  A  piece  of  sand,  brick,  clay,  or 
such  material  embedded  in  metal  would  be  considered  as  a  for- 
eign body,  not  as  an  impurity,  and  therefore  not  a  sonim."  A 
brief  discussion  of  their  occurrence  will  be  given  under  Micro- 
structure.  Manganese  sulphide,  MnS;  iron  sulphide,  FeS;  iron 
oxide,  FeO,  Fe2Oi,  rarely  Fe2Os;  iron  or  manganese  silicate, 
various  proportions;  iron  phosphide,  Fe3P  and  Fe2P;  iron  silicide, 
FeSi;  various  carbides  either  free  or  partially  replaced  by  iron, 
as  manganese  carbide,  MnsC,  also  (FeMn)sC;  chromium  carbide 
Cr2Cs,  etc.  Kirner  claims  to  have  found  a  constituent  in  steels 
rich  in  nitrogen  which  he  calls  flavite,  perhaps  iron  nitride, 


Hardening  Theories.  —  Various  explanations  have  been  offered 
to  attempt  to  explain  why  steel  may  at  one  time  be  soft  and  at 
another  hard.  Howe  states  that  "Hardening  is  usually  due  to 
martensitization,  that  is,  to  enabling  the  transformation  to  pro- 
ceed to  but  not  past  the  martensite  stage,  either  (i)  by  cooling  car- 
bon steels  rapidly  from  the  austenite  state;  or  (2)  by  the  presence 
of  such  an  intermediate  proportion  of  the  obstructing  elements, 
carbon,  nickel  and  manganese,  as  to  cause  the  transformation  to 
reach  only  this  stage  even  in  slow  cooling;  or  (3)  by  bringing  it 
to  this  stage  by  subcooling  cold  austenitic  steel,  e.g.,  in  liquid  air; 
or  (4)  by  overstraining  austenitic  steels  by  cold  deformation,  so 
as  to  stimulate  the  overdue  change  from  the  austenitic  to  the 
martensitic  state.  In  addition  to  these  four  martensitizing 
methods  of  hardening  there  are  two  others,  which  we  may  call  (5)- 
and  (6).  (5)  is  the  hardening  of  austenitic  steels  by  a  regulated 
reheating,  which  gives  mobility  enough  to  allow  the  transforma- 
tion to  go  as  far  as  the  hard  intermediate  state,  but  not  enough  to 
let  it  reach  the  final  alpha  state.  This  hardening  does  not  always 
cause  martensitization.  (6)  is  the  hardening  of  the  malleable 
metals  and  alloys  in  general,  gamma  and  alpha  iron  included,  by 
plastic  deformation.  There  is  neither  evidence  nor  reason  for 
believing  that  this  usually  acts  through  martensitization,  except 
in  the  case  of  gamma  iron"  (Metallography  of  Steel  and  Cast  Iron, 
176-7).  Howe  calls  groups  (i)  to  (5)  the  reversing  class,  and 
(6)  the  cumulative  class;  (i),  (3)  and  (4)  are  also  referred  to  as 
dynamic.  Sauveur  (Metallography  and  Heat  Treatment  of  Iron 
and  Steel,  p.  308)  makes  a  general  division  into  retention  theories 
(where  a  former  state  is  more  or  less  preserved)  and  stress 
theories;  he  also  refers  to  solution  theories  which  involve 
some  form  of  solid  solution  (sometimes  referred  to  as  forced 
solution),  and  carbon  theories  where  carbon  as  such  (or  in  com- 
bination) is  assumed  to  be  responsible. 

Osmond's  theory,  also  referred  to  as  the  allotropic,  beta  or 
beta  iron  theory  is  based  on  the  assumption  that  in  passing  from 
the  gamma  state  above  Ar3,  to  the  alpha  state  below  Ar\,  some 
of  the  iron  is  retained  in  the  hard  beta  form.  Osmond  states,  "I 
conclude  that  hardened  steel  owes  its  properties  principally  to 
the  presence  of  beta  iron,  which  is  hard  and  brittle  by  itself  at 


280  METALLOGRAPHY 

the  ordinary  temperature."  In  view  of  certain  results  of  Had- 
field  and  Hopkinson,  Howe  suggests  the  possibility  that  "in1 
addition  to  the  non-magnetic  beta  iron  as  we  know  it  above  A  2, 
.  .  .  there  is  a  fourth  allotropic  form,  hard  and  yet  magnetiz- 
able in  strong  fields  which  we  may  call  beta  II.  On  this  hypothe- 
sis, .  .  .  the  transformation  is  really  divisible  into  two  parts, 
so  that  the  hard  state  .  .  .  represents  beta  I  mixed  with 
gamma,  and  that  of  quenched  steel  represents  beta  II  mixed  with 
alpha"  (Metallography  of  Steel,  186).  Again  (p.  196),  in  regard 
to  the  beta  theory  or  hypothesis,  "that  it  is  a  distinct  beta  state 
or  states  of  iron,  coordinate  with  the  end  states  gamma  and  alpha. 
Gamma  iron  alone  is  dense,  beta  I  and  II  alone  are  hard,  and 
beta  II  and  alpha  alone  are  magnetic,  both  gamma  and  alpha 
being  isolated  easily,  but  beta  thus  far  always  occurring  mixed 
with  either  gamma  or  alpha  or  more  often  both."  Benedicks' 
theory  is  that  so-called  beta  iron  is  really  a  solution  of  gamma  fer- 
rite  in  alpha  ferrite.  The  gamma  or  gamma  iron  theory  ignores 
the  existence  of  beta  iron  and  assumes  that  a  certain  amount  of 
gamma  iron  is  preserved  in  solution  in  alpha  iron.  The  alpha  or 
alpha  iron  theory  of  LeChatelier  and  Guillet  is  that  in  cooling, 
carbide  of  iron  is  retained  in  solution  in  alpha  iron. 

The  carbon  theories  of  hardening  are  directly  opposed  to  the 
preceding,  being  based  on  the  contention  that  the  hardening  is 
the  result  of  the  carbon,  per  se,  and  not  directly  at  least  to  any 
allotropic  condition  of  the  iron.  In  support  of  this  view  it  is 
pointed  out  that  without  any  carbon  iron  cannot  be  usefully 
hardened,  while  the  effect  increases  with  increase  in  carbon,  at 
•  least  to  a  certain  point.  The  hardening  carbon  theory  asserts 
that  above  A  3  the  carbon  exists  in,  and  imparts  to  the  steel,  a 
hardened  condition  which  can,  in  part  at  least,  be  retained  when 
cold  by  sufficiently  rapid  cooling.  Arnold's  sub-carbide  theory 
supposes  the  existence  above  A3  of  a  sub-carbide  having  the 
formula  Fe24C,  called  hardenite,  which  is  very  hard,  and  if 
retained  when  cold  imparts  this  property  to  the  steel.  There 
was  also  the  diamond  theory,  that  hardness  was  produced,  on 
quenching,  by  the  carbon  being  converted  into  minute  diamonds 
by  the  sudden  compression  of  the  metal. 

The  carbo-allotropic  theory,  in  the  nature  of  a  compromise 
between  the  two  proceeding,  is  that  hardening  is  due  both  to 
the  allotropic  condition  of  the  iron,  and  to  carbon  in  solution, 
probably  as  carbide  but  perhaps  as  simple  carbon,  which  acts 
as  a  brake  on  the  transformation  which  is  thus  largely  prevented 
when  the  cooling  through  the  transformation  range  is  sufficiently 
rapid. 

Stress  Theories  of  Hardening. — In  this  connection  a  careful 
distinction  must  be  made  between  (a)  macroscopic  strain,  that 
produced  by  irregularities  of  cooling  a  mass  or  object,  which 
affects  different  parts,  and  may  result  in  actual  rupture;  and 
(b)  microscopic  strain,  which  affects  the  component  particles 
of  the  grains.  Akerman's  theory,  that  hardening  is  due  to 
compressive  strains  alone  (compression  theory),  set  up  by 
quenching  or  other  rapid  cooling  is  no  longer  considered. 


METALLOGRAPHY  281 

Beilby's  theory  was  that  the  hardness  in  cold-strained  metals, 
as  in  the  case  of  wire  drawing  or  of  polishing,  was  due  to  a 
vitreous  amorphous  phase,  or  thermally  metastable  state, 
sometimes  referred  to  as  Beilby's  hard  iron.  Somewhat  along 
the  same  line,  Rosenhain  and  Ewen  ^uggest  that  the  space 
between  the  boundaries  of  crystal  faces  is  filled  with  an  amorph- 
ous material  or  cement  (see  Plastic  Deformation  below). 
Humfrey's  amorphous  theory  is  that  this  amorphous  condition 
is  brought  about  by  cooling  rapid  enough  to  prevent  one  crystal- 
lized form  to  recrystallize  (decrystallization)  into  the  other 
whereby  there  results  an  amorphous  solution  of  carbide  of  iron 
in  alpha  iron;  the  hardness  would  therefore  be  due  not  only  to 
that  of  the  amorphous  phase  but  also  to  the  iron  carbide  solution. 
The  amorphous  theory  or  stress  theory  in  some  form  is  also  held 
by  Edwards  and  Carpenter,  A.  Le  Chatelier,  Grenet,  and  Charpy. 
McCance's  interstrain  theory  is  somewhat  similar  as  he  claims 
that  there  is  a  solution  of  carbon  in  alpha  iron  (transformed 
from  gamma  iron)  with  some  gamma  iron;  that  the  iron  is 
crystalline  but  in  a  condition  of  strain  due  to  the  arrangement 
between  the  alpha  and  the  gamma  iron,  for  which  he  uses  the 
term  interstrain  to  denote  the  condition  of  a  metal  after  perma- 
nent deformation  of  any  kind;  other  writers  have  used  the 
terms  internal  tension  and  internal  strain. 

Plastic  Deformation. — When  a  metal  is  subjected  to  any  kind 
of  static  stress  it  is  deformed  (a)  temporarily  if  the  stress  is 
within  the  elastic  limit,  and  (&)  permanently  if  the  stress  is 
above  the  elastic  limit,  provided,  of  course,  it  is  plastic  which 
is  the  case,  to  a  certain  extent,  at  least,  with  all  metals  (see 
Physical  Properties,  page  334).  Such  plastic  static  deformation 
caused  by  overstrain,  is  due  to  an  actual  flow  of  the  material. 
Howe  and  Levy  (T.  A.  I.  M.  E.,  L)  distinguish  four  varieties; 
(i)  intergranular,  where  the  several  grains,  each  as  a  unit,  move 
with  relation  to  each  other;  (2)  intra-granular,  where  the  par- 
ticles of  ferrite,  cementite,  or  pearlite,  each  as  a  unit,  move  with 
relation  to  each  other;  (3)  intra-pearlitic,  where  the  pearlitic 
ferrite  and  cementite  move  with  relation  to  each  other;  and 
(4)  crystal  unit  slipping,  where  the  minute  units  move  past 
each  other.  Howe  (Metallog.  of  Steel,  293-4)  further  divides 
them  into  fluid  movements,  where  the  individual  particles 
move  with  relation  to  all  the  others,  and  block  movements, 
where  the  motion  is  by  portions,  the  particles  in  each  being 
relatively  stationary;  the  movement  may  also  be  crystalline, 
if  it  is  concerned  with  crystalline  structure,  and  non-cry stalline 
if  without  such  regard;  crystalline,  again,  may  be  rotary  (change 
of  position  and  of  orientation),  and  vectorial  (change  of  position 
without  change  of  orientation). 

Amorphous  Cement  Theory. — Beilby's  theory  of  crystalline  slip 
was  that  when  a  metal  was  overstrained  it  assumed  a  temporary 
fluid  or  mobile  state  and  then  an  amorphous  phase  or  state 
which  was  located  between  the  crystal  boundaries  and  acted  as 
a  cement  (this  name  seems  appropriate  as  it  requires  an  appre- 
ciable time  for  it  to  "set")  to  bind  them  together  (intergranular 


282  METALLOGRAPHY 

cement),  the  amount  being  in  proportion  to  the  overstrain;  this 
cement  is  supposed  to  be  much  harder  and  stronger  than  the 
crystalline  material  which  it  joins.  This  amorphous  phase  is 
regarded  by  Rosenhain  and  others,  from  the  point  of  view  of  the 
phase  rule,  as  identical  with  the  liquid  phase.  This  cement 
or  amorphous  boundary  filling  may  lead  to  what  Howe  terms 
boundary  or  joint  strength  which  in  normal  conditions  leads 
to  rupture  through  the  grains  (transcrystalline)  instead  of 
following  (intergranular)  the  boundaries  themselves.  Rosen- 
hain holds  that  there  is  a  dendritic  interlocking  of  the  adjacent 
grains  which  increases  the  strength  when  present;  there  is  also 
evidence  (Howe)  that  there  is  contact  confusion  of  orientation 
(strong  contact-metal  theories).  Howe  points  out  (Metallog. 
of  Steel,  191-2)  that  amorphizing  (becoming  amorphous)  may 
be  either  mechanical  by  cold  working  or  overstrain,  or  crystal  - 
lographic,  by  the  occurrence  of  the  transformation  in  cooling 
at  so  low  a  temperature  that,  on  the  breaking  up  of  the  gamma 
iron  crystals  by  the  transformation  itself,  the  resultant  alpha 
iron  particles  cannot  re-orient  themselves  and  hence  remain 
amorphous.  According  to  Howe  and  Levy  (loc.  cit.),  while 
Beilby's  theory  satisfactorily  explains  the  phenomena  of  simple 
overstrain  (stress  applied  in  one  direction),  it  does  not  in  the 
case  of  reversing  overstrain  (first  in  one  direction  and  then  in 
the  opposite),  as  the  former  strengthens  the  metal  and  its  effect 
can  be  obliterated  by  annealing  at  a  relatively  low  temperature, 
while  the  latter  does  not  strengthen  the  metal  nor  is  its  effect 
obliterated  by  such  treatment. 


D  D 

A  -Before  Straining  B-  After  Straining 

PIG.  40. — Diagram  of  the  formation  of  slip  bands  (Rosenhain). 

The  work  of  Ewing  and  Rosenhain,  followed  by  that  of  others, 
has  served  to  explain  the  mechanism  of  plastic  deformation. 
This  occurs,  when  the  local  elastic  limit  has  been  exceeded,  by 
the  slipping  of  one  layer  or  portion  of  a  crystal  or  grain  over 
another  portion  along  slip  planes,  gliding  planes  or  cleavage 
planes  (motion  planes),  an  interstratal  (between  strata)  move- 
ment, producing  what  are  known  as  slip  bands  (Ewing  and 
Rosenhain' s  slip  theory).  These  are  shown  in  Fig.  40.  (Rosen- 
hain, Phys.  Met.,  243)  "which  is  intended  to  indicate  in  a  very 
approximate  manner  the  condition  of  a  cross -section  of  two 
adjacent  crystals  before  and  after  plastic  straining.  The  upper 
sketch  represents  the  unstrained  crystals,  whose  smooth  upper 
(polished)  surface  is  indicated  by  the  line  ABC — the  step  at 
B  is  the  slight  difference  of  level  between  adjacent  crystals 
formed  as  the  result  of  etching;  the  boundary  between  the 


METALLOGRAPHY  283 

crystals  is  represented  by  the  full  line  BD,  while  the  potential 
planes  of  gliding  or  slip,  differently  oriented  in  each  crystal,  are 
indicated  by  the  dotted  lines.  After  straining,  slip  has  taken 
place  on  some  of  these  slip  planes,  and  minute  steps  have  con- 
sequently been  formed  in  the  surface  at  the  points  marked 
s,  s,  s  in  the  lower  figure — these  steps  will,  of  course,  slope  in 
different  directions  in  different  crystals.  Seen  from  above,  by 
normal  illumination,  these  short,  steep,  sloping  surfaces  will 
appear  simply  as  narrow  black  lines"  (Rosenhain,  Phys.  Met., 
243-4).  Simple  slip  or  primary  slip  is  where  only  one  has 
occurred;  secondary  slip  is  where  there  has  been  further  slipping. 
As  the  straining  is  increased  up  to  the  point  of  rupture  the  bands 
become  more  numerous  and  confused,  with  a  roughening  of  the 
surface  apparent  to  the  naked  eye.  This  appearance  is  some- 
times termed  micro-flaws.  The  result  of  the  internal  strains 
produced  by  plastic  deformation  is  indicated  by  surface  de- 
formations or  bands  (flow  lines  or  lines  of  stress),  which  have 
been  called  Liiders  lines,  corresponding  with  slip  bands;  they 
differ  from  the  Neumann  ban4s>or  narrow  twins  (see  Crystal- 
lography, page  127)  in  that  they  are  obliterated  by  etching. 

1.  Close  order  in  line  2.  Open  order  en  echelon 


FIG.  41. — Varieties  of  slipping. 
(Howe  and  Levy.) 

Howe  uses  the  term  common  lines  (loc.  cit.,  298-9)  and  common 
paths  of  deformation  as  those  which  are  of  the  same  family  as 
the  theoretical,  based  on  the  nature  and  direction  of  the  forces 
acting;  and  specific  lines  or  paths,  those  actually  followed, 
differing  materially  from  the  theoretic  by  reason  of  internal 
surfaces  of  weakness.  Howe  and  Levy  (T.  A.  I.  M.  E.,  L,  542) 
illustrate  in  Fig.  41  two  types  of  slipping  which  they  call 
respectively  close  order  in  line  and  open  order  en  echelon ;  they 
state  that  if  the  alternate  strata  are  brittle,  compression  parallel 
to  the  stratification  converts  the  first  into  the  second. 

Howe  states  (Metallog.  of  Steel,  312-3)  "In  a  given  grain  the 
slip  bands  usually  have  a  dominant  direction,  which  may  be 
followed  closely,  as  when  the  slip  bands  are  both  closely  parallel 
and  nearly  straight,  or  may  be  deviated  from  materially.  In 
this  deviation  the  slip  bands  may  remain  nearly  parallel,  in 
which  case  the  deviation  is  of  the  whole  system  of  slip  bands,  a 
systematic  deviation;  or  they  may  deviate  independently  of 
each  other,  giving  us  individual  deviations.  By  the  terminal 
grain  boundaries  I  mean  those  toward  which  the  dominant 
direction  of  the  slip  bands  runs ;  by  the  lateral  ones  I  mean  those 
along  which  it  runs."  Howe's  explanation  of  Osmond  and 
Cartaud's  Slip  Band  Theory  is  as  follows  (Metallog.  of  Steel, 
339);  it  is  "in  effect  incomplete  twinning,  a  rocking  or  rotating 


284  METALLOGRAPHY 

of  the  units  which  compose  each  of  the  slices  of  metal  involved 
in  the  movement,  each  unit  about  its  right-hand  side,  together 
with  a  lifting  of  each  unit  by  its  own  rocking  and  by  that  of 
those  at  its  right.  ...  In  this  view  there  is  no  slip  plane,  but  a 
succession  of  gliding  planes.  .  .  .  The  direction  of  the  motion 
is  approximately  normal  to  the  riser  [of  the  step],  instead  of  being 
parallel  to  it  as  in  simple  slip.  This  may  be  called  the  wheeling 
[slip  theory]  as  distinguished  from  Ewing  and  Rosenhain's 
slip  theory  of  slip  bands." 

Metallographic  Examination. — The  methods  are  as  various 
as  opportunity  offers  or  expediency  indicates.  They  may  be 
classified  into: 

(1)  Optical   analysis:  Determining   the   constituents,   struc- 
tures, forms,  appearances,  etc.,  by  the  eye  alone  or  assisted  by 
suitable  magnifying  devices. 

(2)  Thermal  analysis:  A  study  of  the  nature  of  metals  and 
alloys   by  means   of  heating  and  cooling  curves,   changes  in 
specific  heat,  etc. 

(3)  Magnetic  analysis:  Determination  of  changes  in  nature 
affecting  the  magnetic  properties. 

(4)  Physical  analysis:  Determination-  of  the  properties  by 
the  usual  methods  of  testing. 

(5)  Chemical  analysis:  Both  proximate  and  ultimate;  gen- 
erally in  conjunction  with  one  of  the  other  methods. 

Optical  Analysis.— Also  termed  visual  analysis.  This  is 
divided  into  (a)  macroscopic  or  megascopic  analysis,  which 
relates  to  an  examination  of  appearances  sufficiently  large  to  be 
visible  to  the  naked  eye  or  when  enlarged  only  a  few  diameters 
(the  dividing  line  usually  being  placed  at  about  5  diameters); 
subjects  which  belong  to  this  class  are  ordinary  fractures,  certain 
structures,  crystalline  formations,  etc.;  (b}  microscopic  analysis 
where  minute  structures  require  the  aid  of  high  magnifications; 
there  are  various  synonyms  or  associated  terms;  microscopy, 
micrography,  relating  to  the  study  of  minute  objects  by  the 
aid  of  the  microscope;  micrology,  practically  the  same  as  the 
preceding,  except  that  the  examination  need  not  always  be  visual; 
micrometry,  the  measurement  of  minute  objects,  or  quantities, 
quantitative  microscopy;  microtechnique,  the  methods  em- 
ployed; metalloptric,N  microscopy  as  applied  to  metals;  micro- 
metallurgy,  micrology  as  applied  to  metals.  The  minute 
characteristics  are  termed  the  micro -character,  their  formation 
the  microstructure ;  where  the  structure  is  too  minute  to  be 
resolved  by  the  most  (or  any  but  the  most)  powerful  magnifica- 
tion, it  is  said  to  be  ultramicroscopic.  Photographic  reproduc- 
tions are  called  photomicrograph  (frequently  erroneously  micro- 
photograph;  this  really  means  a  photograph  reduced  to  such 
small  size  that  it  must  be  viewed  through  a  magnifying  glass); 
micrograph,  microphotogram  (rare),  photogram,  and  microgram. 
The  terms  visual  microscopy  and  photomicroscopy  or  photo- 
micrography are  sometimes  used  to  distinguish  respectively 
between  the  use  of  the  eye  only  and  photographic  reproduction. 
A  distinction  is  usually  made  (applying  to  macroscopic  work) 


METALLOGRAPHY  285 

between  photograph  and  print;  the  former  is  a  reproduction 
by  photographic  means  (that  is,  indirect),  while  the  latter  is 
by  direct  contact  with  the  object  itself,  as  in  the  case  of  sulphur 
prints.  A  form  of  microscope  particularly  adapted  to  the 
examination  of  metals  has  received  the  special  names  metal- 
lurgical microscope,  metalloscope,  and  micrometallograph 
A  simple  microscope  is  one  which  has  only  one  lens  (or  set  of 
lenses),  a  compound  microscope  is  one  which  has  two  such  lenses, 
one  near  the  object  (objective),  and  the  other  for  the  eye  of  the 
observer  (eye-piece).  The  ordinary  or  single  microscope  has 
only  one  tube,  etc.;  the  binocular  or  stereoscopic  binocular 
microscope  consists  of  two  instruments  mounted  to  give  a 
stereoscopic  (perspective)  view.  As  metal  specimens  are  opaque 
the  light  to  make  the  surface  sufficiently  visible  (illumina- 
tion) cannot  be  transmitted  through  them  but  must  be  directed 
on  the  surface  itself  by  a  reflecting  or  refracting  device  called 
an  illuminator.  Usually,  particularly  with  very  high  powers, 
the  illumination  is  vertical  or  normal,  that  is,  perpendicular 
to  the  surface;  in  some  cases  to  reveal  irregularities  in  the  surface 
by  throwing  projections  into  relief,  an  oblique  illumination 
is  employed  where  the  light  strikes  at  an  angle  less  than  90  de- 
grees. The  picture  of  the  object  shown  by  the  microscope  is 
termed  the  image.  The  power  of  a  microscope  is  usually  ex- 
pressed in  diameters,  that  is,  the  number  of  times  the  linear 
dimension  of  an  object  is  magnified.  To  resolve  a  structure  is 
to  bring  out  its  detail  (constituents,  etc.)  by  the  use  of  a  suffi- 
ciently high  power.  Within  the  past  few  years  the  General 
Eelectric  Company  has  experimented  with  the  x-ray  for  the 
detection  of  internal  defects,  particularly  of  castings.  Radio- 
graphs, employing  Coolidge  tubes,  have  been  made  with  con- 
siderable success;  stereoscopic  radiographs  have  also  been 
made  with  a  view  to  determining  also  the  depth  at  which  the 
defects  occurred. 

Preparation  of  Specimens. — Where  high-power  microscopes 
are  to  be  employed  it  is  necessary  to  have  a  plane  surface  free 
from  all  scratches,  although  for  ordinary  purposes  very  special 
care  and  precautions  are  not  always  necessary.  This  is  effected, 
after  preliminary  preparation  by  cutting  and  filing,  by  polishing, 
an  operation  consisting  in  applying  various  abrasives  (such  as 
emery,  rouge,  etc.)  of  successive  degrees  of  fineness  until  the 
desired  result  is  secured.  It  is  naturally  much  more  difficult 
to  remove  all  scratches  in  the  case  of  very  soft  material  on 
account  of  its  greater  susceptibility  to  being  affected  by  chance 
specks  of  dust,  etc.;  great  care  must  therefore  be  exercised  to 
maintain  cleanly  conditions  and  the  specimen  must  be  carefully 
washed  after  each  step  to  prevent  any  coarse  abrasive  from  being 
introduced  into  the  next  finer  grade;  it  is  also  of  assistance  to 
have  the  direction  of  polishing  at  each  stage  at  right  angles 
to  that  of  the  preceding.  Burnishing  and  buffing  as  ordinarily 
applied  are  simply  comparatively  crude  polishing  operations  to 
produce  a  high  luster  on  articles  of  jewelry,  etc.,  and  usually 
result  in  myriads  of  fine  scratches  and  also  tend  to  smear  the 


286  METALLOGRAPHY 

metal  on  the  surface.  Certain  constituents  are  revealed  by 
polishing  alone  owing  to  differences  in  coloration  (this  is  par- 
ticularly true  of  some  non-ferrous  alloys)  such  as  graphite  or 
manganese  sulphide,  or  where  there  is  a  marked  difference  in 
hardness;  by  using  a  soft  backing  to  carry  the  abrasive  the  softer 
parts  are  worn  away  to  a  greater  depth,  forming  a  bas-relief 
(relief  polishing).  The  treatment  with  different  chemical 
reagents,  etc.,  with  a  view  to  developing  differences  between 
the  various  constituents  by  the  coloration  or  appearance  which 
they  assume  and  the  degree  to  which  they  are  corroded,  is  known 
as  etching. 

Etching. — This  is  usually  done  when  the  specimen  is  cold 
(cold  etching);  however,  methods  have  been  advised  for  use 
when  the  metal  is  at  a  high  temperature  (hot  etching)  in  order 
to  develop  the  structure  when  in  that  condition.  Etching  to 
develop  the  structure  for  subsequent  examination  under  the 
microscope  may  be  termed  microscopic  or  microstructure 
etching;  in  contradistinction  to  this  is  macroscopic  or  macro- 
structure  etching,  which  is  for  the  purpose  of  developing  the 
structure  (such  as  segregation,  porosity,  seams,  etc.)  by  examina- 
tion by  the  eye  alone.  H.  Le  Chatelier  divides  etching  methods 
or  reagents  into  three  classes :  (a)  where  superficial  combination 
with  the  metal  takes  place,  no  solution  occurring;  (6)  where  the 
metal  is  dissolved  and  effects  a  simultaneous  deposition  of  another 
metal;  (c)  where  there  is  simple  solution,  the  crystal  surfaces 
being  developed.  While  "etching"  connotes  a  corroding 
process,  other  methods,  such  as  heat  tinting,  owing  to  the  simi- 
larity of  their  purpose,  are  usually,  and  conveniently,  included 
in  this  classification.  The  various  methods  employed  may  also 
be  classified  as  follows,  according  to  the  means  employed: 

1.  Mechanical  methods:  Polishing  alone;  the  softer  constitu- 
ents are  worn  away  to  a  greater  depth. 

2.  Chemical  methods:  The  different  constituents  are  differ- 
ently affected  in  corrodibility  or  coloration. 

3.  Mechanico-chemical  methods :  Simultaneous  abrading  and 
corroding  action. 

4.  Electrolytic  methods:  An  electric  current  is  employed  to 
assist  in  the  corroding  action. 

5.  Heating  methods:  Thin  oxide  films  of  different  thicknesses 
are  produced,  resulting  in  different  colorations,  or  other  reactions 
are  caused. 

6.  Deposition  methods:  Certain  constituents  are  coated  by 
the  deposition  of  another  metal  in  solution,  with  or  without  the 
assistance  of  an  electric  current. 

7.  Printing    methods:  This    is    included    although    perhaps 
belonging   more   properly   under   methods  of  examination.     It 
consists  in  applying  a  chemical  reagent  which  reacts  on  one  of 
the  constituents  to  form  a  compound  which,  in  turn,  reacts  on 
a  second  reagent  applied  on  a  sheet  of  paper  or  cloth  applied 
directly  to  the  surface  of  the  specimen. 

Mechanical  Methods  of  Etching. — As  already  mentioned 
these  consist  in  using  a  very  soft  backing  for  carrying  the  abra- 


METALLOGRAPHY  287 

sive;  they  are  principally  used  with  non-ferrous  alloys  where 
there  is  a  marked  difference  in  hardness  between  the  various 
constituents. 

Chemical  Methods  of  Etching.— BaykofPs  method,  for  hot 
steel,  is  to  employ  hydrochloric  acid  (HC1)  gas.  Benedicks' 
reagent:  5%  solution  (ale.)  of  metanitrobenzol  sulphonic  acid; 
darkens  martensite  more  than  austenite.  Heyn's  reagents: 

(a)  copper-ammonium  chloride:   10  grams  in   120  c.c.  water; 

(b]  also  ammoniacal  copper-ammonium  chloride:  as  in  (a)  with 
sufficient    ammonia    (NEUOH)    added    to    dissolve -the    blue 
precipitate   which   first  forms;    (c)    (with    Martens)    alcoholic 
hydrochloric  acid:  i  c.c.  hydrochloric   acid    (1.19)    in    100   c.c. 
absolute  alcohol.    Hilpert  and  Colver-Glauert's  reagent:  sul- 
phurous acid;  3  to  4%  of  a  saturated  aqueous  solution  of  sulphur 
dioxide  in  water  or  alcohol.    Igewsby's  (Ischewski)  reagent: 
5  grams  picric  acid  in  100  (also  given  as  95)  c.c.  absolute  alcohol. 
Jones'    reagent:   molten   zinc;   after   immersion  any  adherent 
zinc  or  dross  removed  partly  by  mechanical  means  and  partly 
by    dilute    sulphuric    acid.     Kourbatoff's  reagents:    (a)   3% 
(about)  aqueous  solution  of  sodium  picrate  with  an  excess  of 
caustic  soda  (NaOH);  solution  to  be  used  boiling;   (b)  nitric 
acid  in  a  solution  consisting  of  a  mixture  of  various  alcohols 
etc.    H.  Le  Chatelier's  reagents :   (a)  an  acidulated  aqueous 
solution  of  ferric  chloride;  (b)  an  aqueous  solution  of  potassium 
bitartrate;    (c)  a  mixture  of   equal   parts  of  a  50%   aqueous 
solution  of  sodium  carbonate  and  a  10%  aqueous  solution  of 
lead  nitrate;  (d)  glycerine  for  composing  the  solution  with  nitric, 
hydrochloric,  or  picric  acid;  (e)  phosphorus  reagent,  consisting 
of:  absolute  methyl  alcohol,   100  c.c.,  cupric  chloride  (CuCl2, 
2H2O)  i  gram,  magnesium  chloride  (MgCl2,  6H2O),  4  grams, 
HC1  (cone.)  2  c.c.,  H2O,  18  c.c.     Martens'  reagents:  (a)  4c.c. 
nitric  acid  (1.14)  in  100  c.c.  absolute  alcohol;  (b)  see  Heyn's 
reagents.    Matweieff's  reagent:  boiling,  neutral,  aqueous  solu- 
tion of  sodium  picrate.     Osmond's  reagents:   (a)  tincture  of 
iodine;  (b)  10  %  aqueous  solution  of  hydrochloric  acid.    Portevin's 
method :  etching  first  in  a  solution  of  10  grams  copper-ammonium 
chloride  in  120  c.c.  water,  followed  by  use  of  10%  solution  of 
nitric    acid    in    water.    Robin's   reagent:    saturated    alcoholic 
solution  of  picric  acid.    Rohl's  reagent:  for  ferrous  sulphide 
(FeS),  i%  ^,myl  alcohol  solution  of  organic  acids.     Saniter's 
reagent:  molten  calcium  chloride  for  hot  etching.     Sauveur's 
reagent:    concentrated   ntiric  acid  washed  off  in  a  stream  of 
water.     Sorby's    reagent:    very    dilute    aqueous    solution    of 
nitric    acid.     Stead's    reagents:    (a)    for    phosphorus,    cupric 
chloride,  10  grams,  magnesium  chloride,  40  grams,  hydrochloric 
acid  20  c.c.,  alcohol,  q.  s.,  1000  c.c.;  (b)  20%  sulphuric  acid, 
followed  by  cleaning  in  nitric  acid.    Whiteley's  reagent:  for 
phosphorus,  0.04  gram  cupric  oxide  (CuO)  dissolved  in  6  c.c. 
of  strong  nitric  acid  and  methylated  spirits  added  to  make  up 
200  c.c.    Yatsevitch's  reagent:  for  high  speed  tool  steel,  10  c.c. 
hydrogen  peroxide  solution  (commercial)  mixed  with  20  c.c.  of 
a  10%  aqueous  solution  of  sodium  hydrate. 


288  METALLOGRAPHY 

Mechanico-chemical  Methods  of  Etching. — The  method 
originated  by  Osmond  is  termed  polish-attack  (sometimes 
attack-polishing  and  polish-etching)  and  at  first  consisted  in 
rubbing  the  specimen  on  parchment  (stretched  on  a  board) 
soaked  with  an  aqueous  extract  of  licorice  root  and  calcium 
sulphate;  later  Osmond  and  Cartaud  substituted  a  2%  aqueous 
solution  of  ammonium  nitrate. 

Electrolytic  Methods  of  Etching.— These  consist,  in  general, 
in  making  the  specimen  the  anode  and  employing  a  very  weak 
current,  the  electrolyte  being  composed  of  various  substances. 
The  cathode  is  usually  a  strip  of  platinum  or  a  platinum  dish 
used  as  the  container.  They  may  be  considered  modifications 
of  the  strictly  chemical  methods.  Martens  and  Heyn  employ 
i  c.c.  of  hydrochloric  acid  in  500  c.c.  of  water;  Osmond  recom- 
mended a  gentle  current  in  connection  with  his  chemical  method 
(&).  Weyl's  method  belongs  to  this  class. 

Heating  Methods  for  Developing  Structure. — Heating  a  speci- 
men in  hydrogen,  air,  etc..,  to  develop  the  structure  on  a  polished 
surface,  by  oxidizing  or  otherwise  affecting  the  different  constitu- 
ents, originated  with  Osmond  (heat  relief),  and  was  perfected 
by  Stead  especially  in  his  researches  on  phosphorus,  and  con- 
sisted in  heating  in  air  after  a  brief  preliminary  treatment 
with  dilute  acid;  termed  heat  tinting,  temper  tinting,  or  air 
tinting. 

Deposition  Methods  of  Etching. — Rosenhain  and  Haughton's 
reagent:  ferric  chloride  (Fe2Cle,)  30  grams,  HC1  (cone.)  100  c.c., 
cupric  chloride  (CuClz),  i  gram,  stannous  chloride  (SnC^), 
0.5  gram,  H2O,  i  liter;  a  film  of  copper  is  deposited,  the  thickness 
(and  coloration  produced)  varying  with  the  different  constituents. 

Printing  Methods. — These  methods  are  used  to  illustrate  the 
macrostructure.  A  method,  termed  nature  printing,  has  been 
used  to  a  limited  extent;  the  surface  is  deeply  etched  with  a 
suitable  reagent  from  which  prints  (nature  prints)  are  taken  with 
ink  as  from  a  wood  block  or  copper  etching  in -ordinary  printing 
work.  A  method  for  making  sulphur  prints  was  devised  by 
Heyn  and  Bauer :  a  piece  of  silk,  wet  with  a  solution  containing 
mercuric  chloride  and  hydrochloric  acid,  is  pressed  on  the 
polished  surface  of  the  specimen;  the  acid  acts  on  any  sulphide 
present,  generating  H2S  which,  in  turn,  reacts  with  the  mercury 
salt  to  form  the  black  precipitate  of  sulphide  of*  mercury;  the 
location  and  intensity  of  the  stains  indicate  the  position  and 
(roughly)  the  extent  of  the  sulphur  present.  Baumann's 
method  replaces  the  silk  with  ordinary  photographic  paper 
moistened  with  dilute  sulphuric  acid,  the  hydrogen  sulphide 
generated  forming  similar  dark  spots  by  reacting  with  the 
silver  salt.  Law  applies  a  coating  of  gelatine  impregnated  with 
an  acid  solution  of  a  soluble  salt  of  lead,  mercury,  or  cadmium 
which  forms  a  discolored  precipitate  as  before;  the  result  is 
viewed  under  the  microscope.  Roger's  method  is  designed  for 
the  examination  of  fractures;  it  consists  in  backing  an  emulsion 
of  gelatine  and  silver  bromide  with  clay  which,  after  dipping  in 
acid,  is  applied  and  then  withdrawn. 


METALLO-METALLIC  COMPOUND— METALLURGY   289 

Structures. — The  macrpstructure  may  be  sufficiently  revealed 
by  simply  cutting  the  desired  section,  as  in  the  case  of  blowholes, 
pipes,  and  cracks;  cutting  and  then  polishing  when  the  details 
sought  are  smaller  or  more  obscure;  etching  to  reveal  so-called 
flow  lines  which  indicate  to  a  certain  extent  the  working  to  which 
the  material  has  been  subjected,  particularly  in  the  case  of  cold 
working  or  where  the  material  has  been  severely  distorted,  in 
this  latter  case  assisted  by  the  lines  of  slag  (wrought  iron)  or 
manganese  sulphide  if  much  is  present.  The  macrostructure 
may  also  reveal  the  presence  of  foreign  substances,  such  as 
inclusions  of  dirt  or  slag  in  steel,  or  of  pieces  of  steel  is  wrought 
iron  ^see  also  Fractures).  The  microstructure  is  made  up  of 
crystals  or  grains  (see  Crystallography)  which,  in  turn,  are 
composed  of  constituents  whose  presence  and  arrangement 
will  depend  upon  the  composition  and  heat  treatment.  Various 
types  of  structure  are  considered  more  generally  under  Crys- 
tallography. Non-metallic  inclusions,  such  as  slag,  manganese 
sulphide,  etc.,  are  detected  by  the  absence  of  a  metallic  luster 
when  polished.  Manganese  sulphide  usually  has  a  dove-gray 
color;  owing  to  its  lower  melting  point,  it  occurs  in  globules 
in  castings,  and  also  because  of  its  plasticity,  drawn  out  as  rods  or 
strings  in  worked  material.  Arnold  has  given  the  names  sulphide 
areas  and  sulphp -films  to  microscopic  constituents  containing 
sulphur.  Sometimes  there  is  present  what  is  termed  a  banded 
structure,  consisting  of  a  series  of  bands  or  lines  of  ferrite, 
white  or  slightly  discolored,  and  frequently  containing  such 
inclusions.  These  lines  are  termed  ghosts,  ghost  lines,  ferrite 
ghosts,  phantoms,  shadow  lines,  or  ghost  structure;  if  very 
minute,  micro-ghosts  or  micro-ghost  lines.  These  lines  are 
usually  considered  as  due  to  dissolved  phosphorus  which  has 
expelled  all  carbon  on  slow  cooling,  hence  sometimes  referred 
to  as  phosphorus  banding;  Stead  calls  white  ghost  lines  those 
whose  appearance  he  considers  due  to  cooling  too  rapidly  to 
prevent  the  expulsion  of  all  carbon  from  the  more  phospborized 
areas.  Howe  states  (Metallog.  of  Steel,  563)  in  regard  to  what  he 
terms  the  incompatibility  theory:  "some  seem  inclined  to  ex- 
plain these  phenomena  by  a  supposed  incompatibility  between 
carbon  and  phosphorus,  so  that  austenite  migrates  away  from 
the  phosphoric  bands  when  within  the  transformation  range, 
and  that  cementite  does  when  below  that  range.  In  support  of 
this  the  slower  cementation  of  phosphoric  than  of  non-phos- 
phoric iron  may  be  cited.''  A  considerable  quantity  of  phos- 
phorus may  occur  in  solution  in  the  ferrite;  it  may  also  appear 
free  (free  phosphide)  as  an  iron  phosphide  forming  a  eutectic 
(particularly  in  the  case  of  high  phosphorus  cast  irons). 

Metallo -metallic  Compound. — See  Alloy. 

Metalloid. — See  page  83. 

Metalloptric  (rare). — See  page  284. 

Metalloscppe.— See  page  285. 

Metallurgical  Microscope. — See  page  285. 

Metallurgy. — The  commercial  production,  preparation  and  treat- 
ment of  metals  and  alloys.  • 
19 


2  QO  METALM  AN— METEORITES 

Metalman  (obs.). — A  worker  or  dealer  in  metals. 
Metamagnetic  Alloy. — See  Alloy. 
Metamerism. — See  page  85. 

Metamorphic  Theory. — Of  hardening;  carbon  theory:  see  page  279. 
Metamorphism. — See  page  122. 
Metaral — See  page  264. 
Metastable  Diagram. — See  page  271. 
Metastable  Equilibrium;  Range. — See  page  269. 
Metathetical  Reaction. — See  page  87. 
Metcalf  s  Experiment. — See  page  214. 
Meteoric  Iron. — See  page  291. 
Meteoric  Stone. — See  page  291. 

Meteorites. — Mineral  and  metallic  bodies  of  extra-terrestrial 
origin  found  on  the  earth's  surface.  They  are  recorded  accord- 
ing to  their  geographical  location  (nearest  town,  etc.)  and,  when 
known,  the  date  of  their  fall.  When  discovered  by  means  of 
their  flight  they  are  called  falls;  if  detected  from  the  nature  of 
their  structure,  finds.  According  to  their  form  they  may  be 
designated  codonoid,  bell-shaped;  conoid,  cone-shaped;  cricoid, 
ring-shaped;  gnathoid,  jaw-shaped;  onchnoid,  pear-shaped; 
ostracoid,  shell-shaped;  peltoid,  shield-shaped;  styloid,  columnar 
etc. 

There  are  three  grand  divisions : 

I.  Aerolites :  consisting  largely  of  stony  matter  (principally 
silicates),  and  usually  also  of  a  slight  amount  of  metallic 
matter. 

II.  Siderolites:  a  transition  group,  composed  of  nearly  equal 
parts  of  stony  and  of  metallic  matter,  with  the  metallic 
portion  generally  in  a  sponge-like  mass  enclosing  the  stony 
material  in  the  pores. 

III.  Siderites:  essentially  metallic,  in  the  form  of  an  alloy 
composed  principally  of  iron  with  which  nickel  and  cobalt 
are  always  associated,  and  frequently  also  gold,  platinum, 
lead,  and  some  of  the  rarer  elements  such  as  gallium, 
selenium,  palladium,  etc. 

The  chemical  composition  varies  widely,  as  is  shown  by  the 
following  analyses : 

Aerolite  (Fayette  County) : 

SiO2 37-70% 

Fe 3-47 

FeO 23.83 

A12O3 2.17 

P2Os 0.25 

CaO 2.20 

MnO 0.45 

MgO 25.94 

NiO 1.59 

CoO 0.16 

Co 0.09 

s..» 1.30 


METEORITES  291 

Siderolite  (Liana  del  Inca) : 

Metallic  Earthy 

Fe 89.77%  SiO2 28.08% 

Ni 9.17  A12O3 12.74 

Co 0.61  FeO 42.52 

NiO 2.90 

MnO 0.20 

CaO 9.33 

MgO 1.98 

P2O6 2.25 

Siderite: 

(Welland)  (Puquois) 

Fe 91.17% 88.67% 

Ni 8.54  9-83 

Co 0.06  0.71 

S 0.07  0.09 

Cu 0.04 

P 0.17 

Si Tr. 

C .  . .  : o .  04 

Variods  other  names  and  classifications  have  been  used  or  sug- 
gested. The  terms  aerolite,  siderolite  (abbreviated  from  aero- 
siderolite),  and  siderite  (abbreviated  from  aerosiderite)  were 
suggested  by  Maskelyne;  Daubree  proposed  siderites  for  those 
that  contained  iron,  and  asiderites  for  those  which  did  not;  sider- 
ites were  again  divided  with  decreasing  contents  of  iron  into  holo- 
siderites  (all  iron),  syssiderites,  and  sporadosiderites  (traces). 
Siderites  are  also  termed  irons  and  iron  meteorites;  aerolites 
stones,  stone  meteorites  or  meteoric  stones;  while  siderolites,  a 
transition  between  the  other  two,  may  be  known  as  iron  stones, 
iron-stone  meteorites,  lithosiderites  or  mesosiderites. 

The  metallic  iron  in  meteorites  may  be  referred  to  as  meteoric 
iron  in  contradistinction  to-  ordinary  or  terrestrial  iron.  The 
study  of  this  subject  has  been  called  aerolitics  (Maskelyne), 
astrolithology  (Shepard),  and  meteoritics  (Farrington). 

The  physical  structure  as  revealed  by  the  microscope  after 
polishing  and  (sometimes)  etching  varies  widely,  and  a  great 
many  distinct  classes  are  recognized,  of  which  the  most  important 
for  the  siderites  are  as  follows : 

(i)  Octahedrites,  or  those  with  an  octahedral  structure  com- 
posed of  two  sets  of  parallel  lines  at  right  angles  to  each  other, 
called  the  Widmanstatten  (or  Widmanstattian)  structure  or 
lines.  These  lines  are  due  to  the  presence  of  three  distinct  iron- 
nickel  alloys,  known  as  th^  triad :  (a)  kamacite,  a  broad  central 
band  (containing  from  4.8  to  7.4%  of  nickel),  with  narrow  borders 
of  (6)  taenite  (containing  from  16.7  to  38.1  %  of  nickel),  and  filling 
in 'the  interstices  or  fields  where  these  bands  intersect,  (c) 
plessite,  a  mixture  of  the  other  two.  The  most  prominent  of  the 
secondary  structures  which  occur  in  the  fields  are  referred  to  as 
combs. 


292  METEORITES 

(2)  Hexahedrites,  or  those  with  a  cubic  (isometric)  structure  or 
cleavage,  composed  of  lines  intersecting  at  an  angle  of  120°,  also 
formed  by  the  triad,  and  known  as  the  Neumann  bands  or  lines. 

(3)  Ataxites,  or  those  having  an  interrupted  or  indistinct  struc- 
ture. 

For  a  complete  list  of  the  various  minerals  and  non -metallic 
substances  found,  some  comprehensive  treatise  should  be  con- 
sulted such  as  those  by  Cohen  or  Farrington. 

Aside  from  the  triad  there  are  various  other  alloys,  of  which  the 
more  important  are: 

Cohenite,  from  the  Magura  meteorite,  corresponds  to  the  for- 
mula (Fe,  Ni,  Co)3C,  and  from  the  Glorietta  Mountain  meteorite 
(Fe,  Ni,  Co)4C. 

Troilite,  iron  sulphide,  FeS,  usually  found  as  separate  nodules, 
but  occasionally  in  bands  or  plates. 

Rhabdite,  a  phosphide  of  iron  and  nickel,  sometimes  containing 
cobalt,  for  which  the  formula  is  (Fe,  Ni)3P. 

Daubreelite,  a  sulphide  of  iron  and  chromium. 

Lawrencite,  a  protochloride  of  iron,  generally  found  as  an 
excrescence. 

Schreibersite,  a  phosphide  of  iron  and  nickel;  the  composition 
is,  as  a  rule,  constant,  and  is  expressed  by  the  formula  (Fe,  Ni 
Co)3P;  it  occurs  in  the  form  of  plates,  and  usually  surrounding  all 
nodules  of  troilite. 

Pallasites  which  most  nearly  resemble  iron  meteorites,  consist 
of  a  sponge-like  mass  of  nickel-iron,  the  pores  of  which  are  filled 
with  chrysolite.  The  proportion  of  metal  to  silicate  varies  in 
different  falls  and  in  individuals  of  the  same  fall.  A  structure 
peculiar  to  about  90%  of  all  stone  meteorites  consists  of  rounded 
grains  or  spherules.  These  are  named  chondri  (sing.,  chondrus); 
or  if  very  minute,  chondrules.  Meteorites  largely  made  up  of 
these  are  known  as  chondrites;  if  not,  achondrites.  In  structure 
chondri  may  themselves  be  granular,  porphyritic  or  coarsely  or 
finely  fibrous.  They  may  consist  of  a  single  crystal  individual 
(monosomatic),  or  of  several  individuals  (polysomatic)  (Farring- 
ton). During  their  passage  through  the  atmospheric  envelope 
surrounding  the  earth,  meteorites  become  highly  heated,  and  if 
metallic,  a  certain  amount  of  oxidation  occurs,  part  of  the  mate- 
rial being  lost  in  transit,  and  what  remains  forming  a  crust  or 
coating.  The  term  iron  glass  has  been  suggested  by  Reichenbach 
for  the  fused  oxidized  coating  sometimes  found  on  iron  meteorites. 
Under  the  microscope,  in  section,  the  crust  of  most  iron  meteorites 
presents  three  and  sometimes  four  well-marked  zones.  The  outer- 
most, called  the  fusion  zone,  is  thin  as  compared  with  the 
others;  it  is  glassy,  black,  and  opaque  to  brown  and  transparent. 
Beneath  this  lies  a  broader  transparent  zone  in  which  the  constitu- 
ents 01  the  meteorites  appear  little  if  any  changed,  called  by 
Tschermak  the  absorption  zone.  The  next  and  last  is  a  broad 
zone  of  black,  opaque,  spotted  appearance.  It  may  be  so  broad 
as  to  make  up  four-fifths  of  the  width  of  the  crust;  the  constitu- 
ents of  the  meteorite  appear  in  normal  condition,  but  impregnated 


METEORITICS— MIDDLETON  AND  HAYWARD     293 

with  black,  generally  opaque  matter,  and  is  called  by  Tschermak 
the  impregnation  zone  (Farrington). 

The  surface  furrows  or  pits  in  meteorites  are  termed  piezoglyps. 

Meteoritics. — See  page  291. 

Metric  Scale. — See  page  204. 

Metric  Ton.— See  Ton. 

Meyer  Process. — See  Recarburization. 

Micaceous  Hematite :  Iron  Ore. — See  page  244. 

Micro  (abbrev.). — Microscopic,  etc. 

Microcellular  Structure. — See  page  126. 

Microcharacter. — See  page  284. 

Microchemistry. — See  page  82. 

Microcryptocrystalline. — See  page  126. 

Microcrystalline  (-crystallitic). — See  page  126. 

Microcrystallography. — See  page  126. 

Micro -flaws. — Due  to  slipping:  see  page  283. 

Micro-ghost;  ghost  Line. — See  page  289. 

Microgram. — See  page  284. 

Microgranitoid. — See  page  126. 

Microgranular;  Granulitic. — See  page  126. 

Micrograph. — See  page  284. 

Micrography. — See  page  284. 

Microlite. — See  page  122. 

Micrology. — See  page  284. 

Micromeritic. — See  page  126. 

Micrometallograph. — See  page  285. 

Micrometallography. — See  page  263. 

Micrometallurgy. — See  page  284. 

Micrometer  Caliper:  Gage. — See  page  187. 

Micrometry. — See  page  284. 

Microphotogram :  Photograph. — See  page  284. 

Microporphyritic. — See  page  126. 

Microradiometer. — See  page  205. 

Microsclerometer. — See  page  480. 

Microscope. — See  page  285. 

Microscopic  Analysis. — See  page  284. 

Microscopic  Constituents. — See  page  264. 

Microscopic  Etching. — See  page  286. 

Microscopic  Metallography. — See  page  263. 

Microscopic  Segregation. — See  page  213. 

Microscopic  Strain. — See  page  280. 

Microscopic  Structure. — Or  microstructure:  see  page  284. 

Microscopically  Cellular;  Crystalline. — See  page  127. 

Microscopy. — See  page  284. 

Microspherulitic. — See  page  126. 

Microstructure. — See  pages  284  and  289. 

Microstructure  Etching. — See  page  286. 

Microtechnique. — See  page  284. 

Microtome. — An  instrument  for  mounting  specimens  for  micro- 
scopic examination. 

Middlesboro  Pig  Iron. — See  page  349. 

Middleton  and  Hayward  Furnace. — See  page  380. 


294  MIDDLETON  PROCESS— MIXER 


Middleton  Process. — See  page  502. 

Middlings.— See  page  432. 

Migratory  Elements. — See  page  70. 

Mil. — See  page  187. 

Mild  Cement. — See  page  67. 

Mild  Centered  Steel. — Steel  cast  with  the  center  of  softer  material 
than  the  outside :  see  page  64.  This  term  might  also  be  applied 
to  steel  which  has  had  the  outside  carburized  by  cementing  or 
casehardening. 

Mild  Ferro-Chrome. — See  page  352. 

Mild  Steel.— See  page  455- 

Mild  Tempered. — See  page  231. 

Miles  Dry  Blast  Process. — See  page  31. 

Mill. — (i)  The  equipment  of  a  rolling  mill;  (2)  in  general,  a  steel  or 
other  plant. 

Mill  Bar  (obs.). — Muck  bar  as  distinguished  from  finished  wrought 
iron  or  merchant  bar:  see  page  377. 

Mill  Cinder.— See  Slag. 

Mill  Fix  (Eng.).— See  page  376. 

Mill  Furnace.— See  page  377. 

Mill  Iron. — Pig  iron  suitable  for  puddling  or  for  the  basic  open 
hearth  process. 

MU1  Scale.— See  Scale. 

Mill  Tap.— See  Slag. 

Milliolithic  Ore. — See  page  244. 

Mine  Pig.— See  page  350. 

Mineral. — Ore;  a  term  used  in  mining. 

Mineral  Carbon  Blacking. — See  page  298. 

Mineral  Wool.— See  Slag  Wool. 

Minor  Calorie. — See  page  199. 

Minor  Shrinkage. — See  page  54. 

Minus  Gage.— See  page  186. 

Mirror  Iron. — See  page  355. 

Mirror  Telescope,  Fery. — See  page  207. 

Miscible. — Capable  of  mixing. 

Mispickel. — See  page  245. 

Missing  Carbon. — See  Carbon. 

Mitis  Castings;  Process. — Castings  made  of  steel  to  which  a  little 
aluminum  has  been  added  to  render  it  quiet;  originally  made  of 
steel  manufactured  by  the  Mitis  process:  see  page  113. 

Mitscherlich's  Law. — See  page  121. 

Mixed  Cement— See  page  67. 

Mixed  Crystals. — See  pages  270  and  275. 

Mixed  Gas.— See  page  362. 

Mixed  Process  (rare). — (i)  Duplex  or  other  combination  steel 
process:  see  page  317. 

Mixer. — Sometimes  called  Jones  mixer,  after  the  inventor,  also 
receiver  or  reservoir.  It  is  a  large  vessel  for  holding  molten 
pig  iron,  with  a  capacity  of  about  75  to  300  tons,  and  resembles  a 
tilting  open  hearth  furnace.  It  is  built  of  steel  or  iron  plates 
lined  with  basic  or  acid  material,  and  is  usually  heated  with  gas. 
Working  doors  or  paddling  doors  (Eng.)  are  provided  so  lime  or 


MOBILE  STATE— MOLDING 


295 


scrap  to  be  melted  up  may  be  thrown  in,  etc.  The  pig  iron  as  it 
comes  from  the  blast  furnace  in  ladles  is  poured  in  through  a 
trough,  and  the  vessel  is  emptied  by  tipping  it  sufficiently.  It 
may  have  one  or  all  of  the  following  objects: 

i.  Simply  to  keep  the  iron  molten  until  it  is  desired  for  use. 
'2.  To  obtain  iron  of  more  uniform  composition  by  mixing  the 
product  of  several  blast  furnaces. 

3.  To  effect  a  certain  amount  of  desulphurization.  This  re- 
quires about  an  hour  or  more,  and  a  manganese  content  of  about 
i  %  or  over. 


FIG.  42. — Mixer. 

Mobile  State. — See  page  281. 

Modern  High  Speed  Tools. — See  page  446. 

Module  (obs.). — Modulus. 

Modulus. — (i)  Of  compressibility  or  compresskm :  see  page  334; 
(2)  of  cubic  compressibility:  see  page  335;  (3)  of  elasticity:  see 
page  334;  (4)  of  elasticity  for  shear:  see  page  335;  (5)  of  extensi- 
bility: see  page  335;  (6)  of  flexibility:  see  page  335;  (7)  of  longi- 
tudinal extension:  see  page  335;  (8)  of  resilience:  see  page  335;  (9) 
of  rigidity:  see  page  335.;  (10)  of  rupture:  see  page  477;  (n)  of 
shear:  see  page  33  5;  (12)  of  specific  extension:  see  page  335;  (13) 
of  stiffness:  see  page  335. 

Moffat  Furnace. — See  page  160. 

Moh's  Scale. — Of  hardness:  see  page  478. 

Moisture.— See  Water. 

Molar  Solution;  Volume;  Weight. — See  page  83. 

Mold;  Molding. — Molding  (obs. — melting  cast  iron  in  a  cupola  for 
foundry  work)  is  the  art  of  preparing  molds  (also  called  matrices 


2  96  MOLDING 

— sing.,  matrix — for  special  purposes),  i.e.,  cavities  in  suitable 
materials  which  are  to  be  filled  with  molten  metal  for  the  produc- 
tion of  objects  of  the  desired  shape  known  as  castings  (q.v.}.  The 
reasons  for  casting  instead  of  rolling  or  forging  are  (a)  lower  cost 
in  certain  cases,  (b}  intricacy  of  shape,  and  (c)  with  cast  iron,  the 
impossibility  of  forming  it  in  any  other  way.  Molds  for  castings 
of  cast  iron  or  steel  are  commonly  made  of  Cast  iron  (steel  molds 
have  been  used  to  a  limited  extent)  or  sand;  the  two  first  are  prin- 
cipally for  steel  ingots,  while  the  last  is  for  more  complicated 
pieces,  and  for  very  large  or  special-shaped  ingots.  Sand  molds 
must  be  made  up  new  for  each  casting;  iron  molds  can  be  used 
repeatedly,  and  hence  are  frequently  called  permanent  molds. 
Cast  iron  (rarely  steel)  molds  are  made  by  casting  in  sand  molds, 
consequently  the  preparation  of  the  latter  need  only  be  con- 
sidered. Sand  molds  may  be  either  green  sand,  dry  sand,  or 
loam.  Green  sand  is  sand  in  its  natural  condition,  containing 
some  clay,  and  brought  to  the  proper  degree  of  dampness  (called 
tempering)  to  make  it  adherent.  Dry  sand  is  sand  which  has 
been  heated  until  all  the  moisture  has  been  expelled,  and  is  mixed 
with  a  little  water  and  flour  or  other  substance  which  will  deposit 
carbon  on  heating  and  bind- the  sand  together,  the»  water  serving 
to  make  the  sand  plastic  during  molding;  usually  a  little  fresh 
sand  is  also  mixed  in.  Loam  is  a  clay  with  a  somewhat  lower 
percentage  of  alumina  (see  analyses  at  end  of  section).  Munk 
suggests  restricting  the  meaning  of  steel  molding  sand  to  a  highly 
siliceous,  refractory  sand  used  in  the  steel  foundry;  steel  cleaning 
sand  to  what  is  suitable  for  cleaning,  especially  sand  blasting; 
steel  sand  or  iron  sand  to  fine  grained  sand  used  for  the  best 
kind  of  cleaning,  and  of  much  better  quality  than  the  regular  hard, 
angular,  cleaning  sand. 

Dry  Sand  and  Green  Sand  Molding. — The  cavity  in  the  mold  is 
formed  by  packing  or  ramming  the  sand  around  a  pattern,  usually 
of  wood,  having  the  shape  of  the  casting.  Owing  to  the  contrac- 
tion which  the  metal  undergoes  in  cooling,  it  is  necessary  to  make 
the  cavity,  and  hence  the  pattern,  slightly  larger  than  the  casting 
is  to  be.  To  assist  in  laying  out  the  work,  a  special  rule  (molders' 
rule,  contraction  rule,  pattern  makers'  rule,  or  shrinkage  gage)  is 
used.  This  is  marked  off  in  feet  and  inches  as  usual,  but  really 
measures  slightly  more  than  it  indicates  to  provide  for  the  neces- 
sary contraction  without  the  trouble  of  making  a  separate  calcu- 
lation for  each  dimension  of  the  casting.  Double  shrink  is  the 
extra  allowance  for  contraction  required  in  preparing  a  metal 
pattern  which  is  first  made  from  a  wooden  pattern,  and  the  final 
casting  from  this.  To  permit  of  the  removal  (drawing  or  deliv- 
ery) of  the  pattern  without  unduly  tearing  the  sand  surrounding 
it,  it  must  be  provided  with  a  slight  taper  (strip,  draft,  draught), 
i.e..  it  must  be  larger  at  the  top  than  at  the  bottom.  To  assist 
in  its  withdrawal,  a  hook  is  usually  screwed  into  the  top  by  means 
of  which  it  is  gently  pulled  out,  at  the  same  time  being  rapped 
with  a  hammer  or  piece  of  wood.  Rapping  in  is  where  the  flask 
is  first  filled  with  sand,  a  small  portion  removed,  and  the  pattern 
then  knocked  in.  A  pattern  is  said  to  be  under-cut  when  the 


MOLDING 


297 


bottom  part  is  larger  than  the  top  (the  opposite  of  being  tapered), 
which  prevents  its  removal  from  the  sand,  and  in  this  case 
coring  must  generally  be  resorted  to.  The  sand  is  held  in  a  box 
or  frame  of  wood  or  metal  called  the  flask,  molding  box,  or  cast- 
ing box.  Depending  upon  the  nature  and  the  size  of  the  casting, 
the  flask  is  divided  into  two  or  more  parts;  the  top  is  called  the 
cope  or  case,  the  bottom  the  drag,  bottom  part,  or  nowel  (Eng.), 
and  any  intermediate  parts,  cheeks.  The  various  parts  of  the 


Oope 


Oheek 


Cheek 


Drag 


FIG.  43. — Section  of  flask  and  pattern. 

flask  usually  consist  of  sides  without  any  top  or  bottom,  and  while 
they  are  being  nlled  boards  or  bottom  plates  are  clamped  on  to 
prevent  the  sand  from  falling  out  until  it  is  rammed  into  a  com- 
pact mass. 

If  the  casting  is  small  and  perfectly  simple,  it  may  be  possible 
to  have  the  pattern  in  one  piece,  but  ordinarily  it  is  necessary  to 
divide  it  into  two  or  more  parts  to  facilitate  its  removal  from 
the  sand.  In  ramming  up  the  mold,  the  bottom  part  of  the  pat- 
tern is  laid  with  the  joint  side  down  on  a  board  (bottom  board, 
joint  board,  or  odd  side  board),  the  bottom  part  of  the  flask  is 


298  MOLDING 

inverted  over  it,  and  sand  is  thrown  in  and  rammed  around  the 
pattern  until  the  flask  is  full.  A- board  is  now  laid  on  top,  the 
whole  turned  right  side  up,  and  the  bottom  board  (which  is  now 
on  top)  removed,  exposing  the  joint  side  of  the  pattern  flush  with 
the  sand.  The  other  part  of  the  pattern  is  now  accurately  fitted 
to  this  by  means  of  pegs  in  one  part  fitting  into  holes  in  the  other. 
Over  the  surface  of  the  sand  in  the  drag  a  little  fine  dry  sand 
(parting  sand)  or  powdered  charcoal  is  sifted  to  enable  the  two 
parts  of  the  mold  to  be  separated  later.  The  top  (or  next) 
section  of  the  flask  is  then  put  on,  and  sand  thrown  in  and  rammed 
up  as  before.  When  full,  a  board  is  fastened  on  top,  and  the 
cope  lifted  up  and  turned  over.  The  two  parts  of  the  pattern  are 
now  removed,  the  surface  of  the  sand  smoothed  up  and  repaired, 
and  the  mold  finally  fitted  together  again  ready  for  pouring. 
With  green  sand  molds  this  may  take  place  immediately.  To 
get  the  sand  in  the  best  condition,  the  surface  is  sometimes 
brushed  or  wiped  (swabbed)  with  water  (held  in  the  water  pot  or 
swab  pot)  by  a  brush  or  swab.  The  parts  of  the  mold  are 
clamped  together,  or  heavy  weights  placed  on  top,  to  prevent 
floating,  i.e.,  separation  from  the  pressure  of  the  metal  within, 
which  is  of  much  greater  specific  gravity.  In  the  case  of  dry 
sand  molds,  after  they  are  thus  prepared  they  must  be  dried,  i.e., 
placed  in  a  furnace  called  a  drying  oven  or  drying  stove,  and  kept 
for  some  hours  at  a  temperature  sufficient  to  expel  all  the  mois- 
ture; if  too  high  it.  causes  burning,  when  the  sand  does  not  adhere 
properly,  and  if  it  is  used  again  the  particles  split  up  and  become 
so  fine  that  they  close  up  the  pores  in  the  mold.  In  cases  where 
it  is  not  possible  or  convenient  to  put  the  mold  in  an  oven,  a  port- 
able coke  fire  or  devil  (Eng.)  is  sometimes  set  on  top  of  the  sand 
to  effect  a  more  or  less  superficial  drying.  Better  to  protect  the 
surface  of  the  mold  from  being  worn  away  (washed  or  washed  up) 
by  the  flow  of  molten  metal,  it  is  often  coated  with  facing  sand, 
which  is  made  up  of  new  sand  mixed  with  various  substances  to 
make  it  very  firm  and  smooth.  Blacking,  consisting  of  powdered 
charcoal,  mineral  carbon  (coke),  plumbago  (blacklead  or  graph- 
ite), so-called  patent  blacking  (nearly  pure  carbon  obtained  by 
the  distillation  of  paraffin  oil),  etc.,  is  sifted  dry  (dry  blacking) 
on  the  surface  of  the  mold  by  means  of  a  porous  bag  (blacking 
bag),  to  give  it  a  smooth  finish  and  protect  it  from  the  washing 
action  of  the  metal;  if  mixed  with  water  it  is  called  wet  blacking, 
liquid  blacking,  or  black  wash  coating,  and  is  applied  with  a 
brush,  called  a  wet  brush  to  distinguish  it  from  the  dry  brush  used 
to  dust  loose  sand  from  the  cracks  in  molds.  Green  sand  molds 
are  sometimes  skin  dried  by  applying  some  combustible  liquid, 
such  as  kerosene,  and  igniting  it. 

As  the  metal  during  solidification  and  also  the  mold  always 
evolve  a  quantity  of  gas,  the  walls  of  the  mold  must  be  porous  to 
permit  it  to  escape,  as  otherwise  the  casting  would  be  injured,  at 
least  in  appearance.  The  sand  is  kept  more  or  less  open  and  fire 
holes  are  also  punched  with  a  wire  (vent  wire),  these  holes  being 
termed  vent  holes,  and  the  operation  venting  or  ventilation. 

If  the  molten  metal  is  poured  directly  into  the  top  of  the  mold, 


MOLDING  299 

it  is  called  top  pouring,  and  the  mold  is  said  to  be  an  open  top 
mold;  this  is  the  usual  method  for  casting  ingots.  With  sand 
molds,  however,  this  would  be  apt  to  tear  the  surface,  and  there- 
fore the  metal  is  introduced  through  a  pipe  or  tubular  opening  at 
one  side  called  a  runner,  feeder,  git,  guit,  gate,  ingate,  inset 
sprue,  tedge,  or  pouring  gate  which  connects  with  the  bottom  of 
the  mold  proper  by  an  opening  known  as  a  gate  or  feeding  gate. 
At  the  top  of  the  runner  is  an  enlarged  depression  (pouring  basin) 
to  receive  the  metal  from  the  ladle  and  insure  its  entering  the 
runner  properly.  This  method  is  termed  bottom  pouring  and  the 
mold  a  close  top  mold.  This  latter  does  not  mean  that  it  is 
completely  closed  over,  as  there  is  usually  an  extension  on  top  of 
the  mold  proper  called  the  sinkhead,  lost  head,  or  riser,  and  con- 
nected with  it  by  the  rising  gate  or  flow  gate,  and  used  for  the 
purpose  of  applying  metal  to  fill  up  any  pipe  or  cavity  resulting 
from  the  contraction  of  the  metal  in  the  casting;  the  top  of  the 
riser  is  open  and  serves  to  show  whether  enough  metal  has  been 
poured  into  the  mold.  If  the  top  surface  of  a  casting  is  not 
enclosed  in  the  mold,  it  is  termed  an  open  sand  mold.  If  a 
number  of  molds  are  filled  simultaneously  from  one  central  mold 
(group  casting),  the  latter,  into  which  the  metal  is  poured  directly, 
is  known  as  a  git  mold  (Eng.). 

Coring. — Holes  or  deep  recesses  in  castings  are  formed  by 
inserting  cylinders  or  pieces,  usually  made  of  hard  baked  sand 
or  clay,  called  cores,  after  the  pattern  has  been  removed  from 
the  mold.  A  cod  (Eng.)  is  a  core  of  green  sand.  On  the  pattern 
are  slight  projections  forming  holes  or  core  prints  in  the  walls  of 
the  mold  into  which  the  cores  are  set.  The  cores  are  prevented 
from  shifting  their  position  (floating)  by  metallic  pieces,  called 
chaplets  or  studs,  which  are  fastened  against  them  in  the  sand. 
For  small  sizes  special  nails  with  flat  heads,  called  chaplet  nails, 
molders'  nails,  or  core  nails,  are  used,  which  are  sometimes  sup- 
ported by  a  block  of  wood  (chaplet  block)  previously  driven  into 
the  sand.  Particularly  for  heavy  cores  a  piece  of  iron,  called  an 
anchor  bolt,  may  be  set  inside  the  core  and  run  through  the  core 
print  to  the  outside  of  the  mold  to  which  it  is  fastened.  Where 
more  than  one  core  is  used,  the  main  one  is  called  the  body  core, 
the  others  the  branch  cores.  Where  the  core  is  of  larger  diame- 
ter in  the  middle  than  at  the  ends,  it  is  termed  a  chambered  core, 
belly  (bellied)  core,  or  roach  belly  core.  With  cores  of  large 
diameter  an  iron  bar  (core  bar)  is  put  through  the  middle  to  stiffen 
them.  A  plate  used  to  support  a  number  of  such  bars  in  the  same 
core  is  -called  a  core  plate.  When  the  bars  must  be  very  large 
they  are  made  hollow  with  perforations  for  venting,  and  are 
termed  core  barrels.  To  prevent  the  interior  or  very  large  cast- 
ings cooling  so  much  more  slowly  than  the  exterior,  a  "pipe  is 
sometimes  inserted  through  which  a  stream  of  water  flows;  this 
arrangement  is  known  as  a  water  core.  When  considerable 
pressure  and  washing  action  from  the  metal  must  be.resisted,  the 
cores  may  be  cut  out  of  solid  carbon  (carbon  core)  In  making 
cast-iron  pipes  the  core  barrel  is  usually  wound  with  hay  rope  or 
hay  band  underneath  the  sand  covering,  which  chars  away  and 


300  MOLDING 

so  gives  room  for  the  contraction  of  the  pipe.  Cores  are  usually 
prepared  in  wooden  molds  (core  boxes),  after  which  they  are  dried. 
The  sand,  etc.,  of  which  they  are  composed  is  held  together 
by  a  core  binder  or  core  gum  consisting  of  potato  starch, 
flour,  etc.,  mixed  with  a  little  water.  If  a  core  is  made  in  two 
or  more  separate  sections  these  are  fastened  (pasted)  together  with 
clay  water  (water  thickened  with  clay),  etc.  A  metal  box  in 
which  cores  are  dried  is  called  a  sagger,  saggar,  or  seggar. 

If  portions  of  the  sand  in  a  mold  are  poorly  supported,  nails  or 
brads  (sprigs :  Eng.)  may  be  thrust  through  the  solid  part,  and 
this  operation  would  be  termed  sprigging  or  nailing  (Eng.).  The 
runners  are  sometimes  called  sprues,  but  this  term  is  generally 
restricted  to  the  metal  which  solidifies  in  them  and  which  must 
be  broken  off  the  casting  and  remelted.  To  prevent  the  thick 
and  the  thin  portions  of  irregular -shaped  castings  from  tearing 
apart  during  cooling  due  to  the  thin  portions  solidifying  first  and 
contracting,  while  the  heavier  portions  are  still  molten  or  mushy, 
they  are  connected  or  tied  together  by  bent  bars  or  brackets 
(dogs)  set  in  the  molds  before  pouring. 

Where  it  is  desired  to  hasten  the  cooling  of  certain  parts  of  a 
casting,  (a)  to  make  the  rate  of  contraction  uniform  throughout, 
or  (ft)  with  cast  iron,  to  make  the  surface  hard  by  retaining  most 
of  the  carbon  in  the  combined  condition,  pieces  of  iron  (chills)  are 
inserted  in  the  mold  flush  with  the  surface.  In  the  case  of  cast- 
iron  car  wheels,  where  it  is  desired  to  have  the  tread  hard,  a  device 
known  as  a  contracting  chill  is  employed;  this  is  arranged  with 
metal  segments  mounted  on  an  iron  ring,  the  segments  expanding 
inward  from  the  heat  from  the  casting,  and  remaining  in  contact 
with  it  as  it  cools  and  contracts.  An  iron  mold  for  ingots  might 
be  termed  a  chill  mold,  but  this  name  is  usually  restricted  to  a 
mold  used  for  cast  iron,  and  not  for  steel.  Plate  molding,  used 
principally  for  small  castings,  consists  in  first  casting  a  metallic 
pattern  on  a  metal  plate  to  insure  ease  and  accuracy  of  handling. 
The  pattern  may  be  divided  between  two  plates,  provided  with 
the  necessary  gates,  etc.  A  plate  may  also  be  used  having  a  hole 
exactly  fitting  the  pattern,  through  which  the  pattern  is  with- 
drawn after  ramming,  the  pattern  projecting  a  little  way  above 
the  plate  (stripping  plate).  Reversed  molds  or  ramming  blocks 
are  plaster  or  metal  molds  used  in  some  classes  of  repetition  mold- 
ing work.  The  actual  casting  molds  are  made  from  these  blocks 
direct,  instead  of  from  a  pattern,  and  the  advantage  of  their 
employment  is  that  a  very  large  number  of  molds  can  be  made 
precisely  alike  without  the  labor  of  forming  the  parting  surfaces 
and  runners  and  risers  at  every  molding  (Horner).  Multiple 
molding  is  where  a  number  of  molds  are  piled  one  on  top  of  the 
other  and  connected  with  a  common  runner  by  which  they  are 
filled. 

Loam  Molding  or  Sweep  Molding. — This  method  is  used  for 
producing  objects  having  surfaces  of  rotation,  i.e.,  symmetrical 
circular  sections.  Objects  such  as  large  gears,  round  bottomed 
pots  or  kettles,  blast  furnace  bells,  etc.,  can  be  molded  very 
quickly  and  economically  by  this  method.  Loam  (a  sand  rich  in 


MOLDING  301 

clay)  or  green  sand  is  employed.  The  mold  or  case  is  first  built 
up  with  bricks.  These  are  held  together  and  given  a  first  coating 
with  roughing  loam  or  black  loam,  of  cheap  quality  and  strong 
binding  properties.  A  finer  grade  is  then  used.  A  templet  or 
arm  called  a  sweep  is  fastened  to  and  turned  around  a  bar  as  an 
axis,  which  is  set  in  the  center  of  the  brickwork.  The  lower  edge 
or  surface  of  the  sweep  has  the  shape  which  it  is  desired  to  impart 
to  the  mold,  which  it  imparts  as  it  is  turned  around.  The  drag 
and  the  cope  are  similarly  formed,  except  the  former  is  concave 
while  the  latter  is  convex,  with  a  space  left  between  the  two  (when 
put  together)  corresponding  to  the  thickness  desired  in  the  cast- 
ing. With  gear  wheels,  the  space  between  the  teeth  is  cored  out 
by  hand  or  by  a  machine.  The  sweep  is  also  called  a  strickle 
(Eng.),  and  the  method  of  molding,  strickling,  striking  up,  or 
sweeping  up. 

The  cire  perdu  process  (lost  wax  process,  waste  wax  process) 
is  generally  used  for  small  bronze  work  of  an  artistic  nature.  A 
rough  sand  pattern  of  the  object  is  first  made,  which  is  as  much 
smaller  than  the  object  as  the  thickness  desired  for  the  metal  in 
the  casting,  and  is  then  coated  with  wax  to  the  desired  size,  and 
the  details  finished  by  the  artist.  The  whole  is  placed  in  sand  in 
the  same  manner  as  an  ordinary  pattern,  and  is  heated  so  the  wax 
will  melt  and  run  out.  The  sand  core  remaining  is  held  in  place 
by  wires  run  through  it,  and  the  space  thus  left  is  filled  with 
metal. 

Machine  Molding. — In  many  cases  where  a  number  of  castings 
are  to  be  made  from  the  same  pattern  it  has  been  found  advanta- 
geous to  employ  a  machine  which  quickens  the  operation  of  mold- 
ing, and  also  does  away  with  much  of  the  skill  and  labor  required 
when  it  is  done  by  hand  as  already  described.  The  machine  may 
be  a  squeezer,  in  which  a  squeezer  board,  operated  by  a  lever, 
presses  the  sand  around  the  pattern  in  the  flask,  or  the  pressing 
may  be  done  by  compressed  air  (pneumatic  molding  machine). 
The  removal  of  the  pattern  may  still  be  done  by  hand,  or  better, 
by  a  special  type  of  machine  which  forces  it  either  up  or  down 
through  a  stripping  plate.  In  the  vibrator  machine  the  pattern  is 
removed  by  vibrating  it  very  rapidly  an  extremely  small  amount 
back  and  forth,  so  the  sand  in  the  mold  is  not  disturbed  appreci- 
ably, and  no  stripping  plate  is  necessary.  In  the  jar  machine 
which  is  coming  into  extensive  use,  the  flat  platform  or  platen 
forming  the  top  of  the  machine  is  raised  from  2  to  5",  and  allowed 
to  drop  at  intervals  of  i  to  5  seconds,  depending  upon  the  size  of 
the  machine  and  of  the  flask  to  be  rammed.  The  flask  with  the 
pattern  in  place,  and  filled  with  loose  sand,  is  placed  on  the 
machine,  and  this  jarring  properly  rams  the  mold. 

Floor  sand  is  that  already  used  and  emptied  from  dry  sand 
flasks  and  swept  up  from  the  floor.  A  screen  used  for  sifting  sand 
by  shaking,  operated  by  machine  or  by  hand,  is  termed  a  riddle, 

Following  are  sample  analyses  of  clay,  sand^and  loam: 


German  clay.  .  . 
White  clay  
Black  clay  

.  78 
.  68 
61 

•39 
.90 

.76 

i. 
o. 

•2 

23 
60 
20 

13 

21 
24 

.83 
.  2O 
.40 

o 
o 
o 

.80 
.25 

.40 

0.81 
0.90 
0.92 

Green  sand  
Dunbar  sand  .  . 
Coxey  sand 

.   86 
.   98 
.   96 

•64 
.46 
.05 

O 

3 
o, 
o, 

13 
44 
,40 

6 
o 

2 

•99 
•67 
.80 

0 

.43 

0.07 

Loam  

.    76 

.06 

3 

64 

II 

.66 

o 

.28 

1.42 

302        MOLD  GASES— MONOTRIMETRIC  SYSTEM 

SiO2       Fe2O3    A1203     CaO      MgO     Loss 

4-74 
7-50 
8.60 
2.81 
0.36 

o-75 
6.20 

Mold  Gases  (Howe). — Those  evolved  from  molten  and  solidifying 
iron  at  atmospheric  pressure. 

Molders'  Nail. — See  page  299. 

Molders'  Rule. — See  page  296. 

Molding  Box. — See  page  297. 

Mole. — See  page  83. 

Molecular  Ease. — The  condition  in  which  the  molecules  in  a  body 
are  allowed  to  take  their  normal  or  natural  position. 

Molecular  Friction. — See  page  268.  • 

Molecular  Heat. — See  page  201. 

Molecular  Inertia. — See  page  264. 

Molecular  Motion. — See  page  199. 

Molecule. — See  page  81. 

Moler. — See  page  396. 

Molten. — See  pages  267  and  269. 

Molten  Metal. — Pig  iron  in  the  molten  or  fluid  condition. 

Molybdenum. — Mo;  at.  wt,  96;  sp.  gr.,  8.6.  It  is  never  found  un- 
combined.  The  pure  metal  is  white  and  is  merely  a  chemical 
curiosity.  It  is  obtained  as  an  alloy  with  iron  called  f  erro-molyb- 
denum  (see  page  353),  and  is  used  to  a  certain  extent  in  the 
manufacture  of  special  steels  (see  page  450).  This  name  was 
formerly  a  synonym  for  plumbago. 

Molybdenum  Hardenite. — See  page  275.  „-. 

Molybdenum  Steels. — See  page  450. 

Monad.— See  page  86. 

Monatomic. — See  page  87. 

Monell  Process. — See  page  316. 

Monkey. — (i)  In  a  blast  furnace:  see  page  32;  (2)  in  the  manufac- 
ture of  steel,  the  rods,  called  respectively  long  and  short-tailed 
monkeys,  placed  in  the  cinder  pit,  and  forming  a  frame  to  hold  the 
slag  together  and  allow  it  to  be  taken  out  with  a  crane;  (3)  a 
dolly;  (4)  a  tup. 

Monnot  Process. — See  page  372. 

Monobasic. — See  page  87. 

Monocellular  Structure. — See  page  1 26. 

Monoclinic  System. — Of  crystallization:  see  page  120. 

MonocUnohedral  System.— Of  crystallization:  see  page  120. 

Monodimetric  System. — Of  crystallization:  see  page  120. 

Monometric  System.— Of  crystallization:  see  page  120. 

Monomorphic. — See  page  121. 

Mono  somatic. — £>ee  page  292. 

Monosymmetric  System. — Of  crystallization:  see  page  120. 

Monotrimetric  System. — Of  crystallization:  see  page  120. 


MONOVALENT— MYNE  303 

Monovalent. — See  page  86. 

Monovariant  System. — See  page  327. 

Monotropic  Transformation. — See  page  327. 

Mop. — See  page  115.* 

Morf  Process. — See  page  373. 

Morgan  Mill. — See  pages  412  and  416. 

Morphology. — See  page  121. 

Morphometry. — See  page  121. 

Morse  Optical  Pyrometer;  Thermogage. — See  pageboy. 

Mother  Liquor. — See  page  266. 

Mother  Metal. — See  pages  56  and  266. 

Mother -of -Pearlyte  (obs.). — An  old  name  suggested  by  Howe  for  the 

constitution  of  iron  from  which  pearlite  is  formed  on  further 

cooling. 

Motherless  Pigs. — See  page  342. 
Motion  Plane. — See  pages  123  and  282. 
Mottle.— See  page  433- 
Mottled  Iron;  Pig. — See  pages  342  and  346. 
Mould,  etc.— Mold,  etc. 
Mound. — See  page  181. 
Mouth. — The  top  or  aperture  of  a  blast  furnace,  Bessemer  converter, 

etc. 

Movable  Bottom,  Holley. — See  page  17. 
Moving  Load;  Concentrated  Load. — See  page  468. 
Muck  Bar. — See  page  377. 
Muck  Mill;  Train. — See  page  413. 
Muffle;  Muffle  Furnace. — See  page  183. 
Multicellular  Structure. — See  page  126. 
Multiple  Casting. — See  page  61. 
Multiple  Drawing. — See  page  508. 
Multiple  Isomorphism. — See  page  121. 
Multiple  Molding. — See  page  300. 
Multiple  Proportions. — Law  of:  see  page  85. 
Multiple  Teeming;  Pouring. — See  page  61. 
Multiple  Twinning. — See  page  124. 
Mundic. — See  page  245. 
Munton  Process. — See  page  60. 
Murdock  Converter. — See  page  24. 
Muriatic  Acid. — Commercial  hydrochloric  acid. 
Mushet  (D.)  Process. — (i)  Direct  process:  see  page  144;  (2)  for 

deoxidizing  by  manganese  additions:  see  page  393. 
Mushet  (R.)  Process. — Of  desiccation:  see  page  30. 
Mushet  Steel. — See  page  445. 
Mushy.— See  page  55. 
Mushy  Stage. — See  page  268. 
Mushy  Structure. — See  page  125. 
Muzzle. — The  nozzle  or  end  of  a  tuyere. 
Myne  (obs.). — Mine  (Eng.)  or  ore. 


N. — (i)  Chemical  symbol  for  nitrogen,  q.v.;  (2)  normal,  of  a  solu- 
tion: see  page  83. 

Na. — Chemical  symbol  for  sodium  (Latin,  natrium),  q.v. 

Nb. — Chemical  symbol  for  niobium  (usually  called  columbium)  : 
see  page  84. 

Nd. — Chemical  symbol  for  neodymium:  see  page  84. 

Ne. — Chemical  symbol  for  neon:  see  page  84. 

Ni. — Chemical  symbol  for  nickel,  q.v. 

Nt. — Chemical  symbol  for  niton:  see  page  84. 

No.  2  Iron;  No.  3  Iron. — See  page  378. 

N.  M.  T.  A. — National  Metal  Trades  Association. 

Nailing. — See  page  300. 

Narrow  Twin. — See  page  125. 

Nascent. — See  page  87. 

Nasmyth  Process.— See  page  380. 

Nathusius  Furnace. — See  page  162. 

Native  Bloomary;  Forge  Process. — See  page  144. 

Natural  Condition;  State. — Of  metal,  simply  cooled  after  the  last 
mechanical  (ordinary)  treatment. 

Natural  Corrosion. — See  page  108. 

Natural  Gas. — A  highly  combustible  gas  occurring  in  pockets  or 
caverns  in  the  earth.  In  districts  near  which  it  occurs  it  is  largely 
used  for  metallurgical  purposes  on  account  of  its  high  calorific 
power  and  low  sulphur.  It  consists  almost  entirely  of  marsh  gas 
(methane)  and  hydrogen,  the  following  being  a  representative 
analysis_by  volume: 

Hydrogen 20  % 

Methane 70 

Other  hydrocarbons 6 

Carbon  dioxide i 

Nitrogen 3 

Natural  Hardness. — See  Hardness. 

Natural  Steel. — (i)  Old  name  for  "steel"  made  direct  from  ore;  (2) 

tool  steel:  see  page  446. 
Nature. — Come  to  nature:  see  page  376. 
Nature  Prints. — See  page  288. 
Nau  Process. — (i)  Casting  process:  see  page  61;  (2)  purification 

process:  see  page  387. 
Nealing  (obs.). — Annealing. 
Neck. — Of  a  roll:  see  page  403. 
Necking. — Of  a  test  piece:  see  page  336. 
Needle  Fracture. — See  page  178. 
Needle-shaped  Crystal. — See  page  126. 
Negative  Crystal. — See  page  127. 
Negative  Hardening:  Quenching. — See  page  231. 
Negative  Segregation. — See  page  56. 
Nerve  Structure. — See  page  125. 

3°4 


NESH— NITROGEN  305 

Nesh  (Eng.). — Tender  or  brittle,  as  of  tin  plates. 

Nested. — Of  crucibles:  see  page  112. 

Net  Structure. — See  page  126. 

Net  Ton.— See  Ton. 

Network  Size;  Structure. — See  page  126. 

Neuberg  Process. — See  page  63. 

Neumann  Bands ;  Lamellae ;  Lines;  Structure. — See  pages  127  and 
292. 

Neutral. — (i)  Of  oxidized  materials,  neither  acid  nor  basic;  (2)  of  a 
flame,  neither  oxidizing  nor  reducing;  (3)  of  wrought  iron,  neither 
red-short  nor  cold-short  (rare). 

Neutral  Axis. — See  page  337. 

Neutral  Coke. — See  page  97. 

Neutral  Lining. — See  Lining. 

Neutral  Moment. — In  solidifying:  see  page  54. 

Neutral  Refractories. — See  page  398. 

Neutral  Siemens  Process. — See  page  310. 

Neutral  Surface. — See  page  337. 

Neutralizing. — Of  phosphorus:  see  page  385. 

Neville  Process. — See  page  144. 

New  Tool  Steel.— See  page  446. 

Newland's  Law  of  Octaves. — See  page  85. 

Newton's  Law  of  Cooling;  Radiation. — See  page  200. 

Newton  Process. — (i)  Cementation  process:  see  page  73;  (2) 
crucible  process:  see  page  118;  (3)  direct  process:  see  page  144. 

Nichrome. — The  trade  name  for  an  alloy  containing  approximately 
nickel  60%,  chromium  14%,  with  the  remainder  chiefly  iron.  It 
is  largely  used  for  parts  exposed  to  high  temperatures  owing  to  its 
comparative  freedom  from  oxidation  and  change  of  form. 

Nick  Bend  Test.— See  page  476. 

Nick  and  Break  Test.— For  rails;  see  page  483. 

Nickel. — (i)  Influence  on  corrosion:  see  page  366;  (2)  commercial 
nickel:  see  page  353. 

Nickel.— Ni;  at.  wt.,  58.5;  melt,  pt.,  1435°  c-  (26l5°  F.);  sp.  gr., 
8.6  to  8.93.  It  is  not  found  in  the  free  state,  but  usually  com- 
bined with  sulphur  or  oxygen.  It  is  a  lustrous  white  metal  with  a 
slight  yellow  tinge  when  compared  with  silver.  It  is  hard,  strong, 
ductile,  and  malleable.  It  is  obtained  in  the  metallic  condition 
(nearly  pure)  or  as  an  alloy  with  iron,  called  ferro-nickel  (see 
Page  353),  and  is  used  in  the  manufacture  of  nickel  steel  (see 
page  450). 

Nickel-Chrome  Steels. — See  page  451. 

Nickel-Ferrite. — See  page  272. 

Nickel  Plating.— See  page  371. 

Nickel  Steel.— See  page  450. 

Nickel  Steel  Armor  Plate.— See  page  8. 

Nipper.— See  page  508. 

Nitric  Acid. — For  etching:  see  page  287. 

Nitro-Cyanide  of  Titanium. — See  Salamander. 

Nitrogen.— N;  at.  wt.,  14;  melt.  pt.,-2i3°  C.  (  — 351°  F.);  boil,  pt., 
-195-5°  C.  (-319-9°  F-);  sp.  gr.,  0.973  (air  =  i);  i  liter  weighs 
1.250  grams.  It  is  a  colorless,  odorless,  and  tasteless  gas,  and  its 
20 


306  NOBBIN— NORMAL 

principal  occurrence  is  in  air,  of  which  it  constitutes  about  four- 
fifths  by  volume,  mechanically  mixed  with  oxygen.  It  combines 
directly  with  very  few  of  the  elements,  and  separates  readily  from 
many  of  its  compounds,  often  with  explosive  violence.  It  is 
found  in  iron,  apparently  forming  a  feeble  compound,  which 
tends  to  make  the  metal  brittle;  it  is  removed  by  the  action  of 
titanium  or  vanadium. 

Nobbin  (rare). — A  bloom  of  puddled  iron  worked  under  the  ham- 
mer. 

Nobbing. — See  Forging. 

Nobili's  Thermopile. — See  page  207. 

Noble  Furnace. — See  page  162. 

Noble  Metal. — See  page  84. 

Noble  Metal  Couple. — See  page  209. 

Nodulizing. — See  page  45. 

Non-acicular  Martensite. — See  page  276. 

Non-anodic  Passivity;  Polarization. — See  page  364. 

Non-Bessemer  Ore. — See  page  243. 

Non-caking  Coal.— See  Coal. 

Non-coking  Coal.— See  Coal. 

Non-continuous  Combustion. — See  page  202. 

Non-corro  Steel. — See  page  451-. 

Non-crystalline. — See  page  119. 

Non-crystalline  Movement. — See  page  281. 

Non-eutectic  Cementite. — See  page  273. 

Non-eutectoid  Cementite. — See  page  273. 

Non-eutectoid  Ferrite. — See  page  272. 

Non-ferrous  Alloy. — See  Alloy. 

Non-ferrous  Structure.— Differing  from  that  of  ordinary  (plain 
carbon)  ferrous  metals;  as  of  alloy  steels  or  cast  irons. 

Non-homogeneous  System. — See  page  328. 

Non-magnetic  Steels. — See  page  445. 

Non-malleable. — Of  metals,  not  capable  of  being  worked  to  a  useful 
degree. 

Non-metal ;  Non-metallic. — See  page  83. 

Non-phosphoric  Pig. — See  page  344. 

Non-refractory  Clays. — See  page  396. 

Non-reversible. — Of  alloys,  processes  and  transformations:  see 
pages  265  and  327. 

Non-reversing  Mill. — See  page  408. 

Non-variant  System. — See  page  327. 

Non-Walloon  Processes. — See  page  75. 

Noodle. — See  page  17. 

Nordman's  Heterochrome  Photometer. — See  page  208. 

Noric  Iron. — An  iron  formerly  manufactured  in  what  are  now 
Styria  and  Carinthia;  it  is  mentioned  by  various  classical  writers. 

Normal. — (i)  Of  material  which  has  been  finished  in  the  usual 
manner  in  contradistinction  to  that  which  has  received  special 
treatment;  (2)  in  connection  with  the  phase  rule:  see  page 
326;  (3  perpendicular;  at  right  angles;  (4)  of  illumination^  for 
microscopic  work;  vertical;  (5)  regular  or  standard;  (6)  average 
or  mean,  as  normal  temperature. 


NORMAL  CARBIDE— NYHAMMER  BLOOMARY    307 

Normal  Carbide. — See  page  272. 

Normal  Pearlite. — See  page  273. 

Normal  Scale. — Of  temperatures:  see  page  205. 

Normal  Solution. — See  page  83. 

Normal  Steel  (rare). — Plain  carbon  steel. 

Normal  Stress. — See  page  332. 

Normal  System. — See  page  326. 

Normal  Thermometer. — See  page  205. 

Normalizing. — See  page  232. 

Norris  Wear  Test. — See  page  480. 

Northrup's  Ratiometer. — See  page  208. 

Norton  Process. — See  page  65. 

Nose. — (i)  The  top  section  of  a  Bessemer  converter:  see  page  17; 
(2)  the  lip  of  a  ladle;  (3)  the  blunt  end  of  a  die  or  hammer;  (4)  an 
accumulation  of  chilled  material  around  the  inner  end  of  a 
tuyere  in  a  smelting  shaft  furnace,  protecting  and  prolonging  the 
tuyere  (Raymond). 

Nose  Helve. — See  Hammer. 

Notch  Gun. — For  a  blast  furnace:  see  page  37. 

Notch  Toughness. — See  page  482. 

Nowel.— See  page  297. 

Nozzle. — See  Ladle. 

Nucleus. — Core;  see  page  67. 

Number.— In  wire  drawing:  see  page  509. 

Nut  Coal.— See  Coal. 

Nyhammer  Continuous  High  Bloomary. — See  page  144. 


o 

O« — Chemical  symbol  for  oxygen,  q.v. 
®s' — Chemical  symbol  for  osmium:  see  page  84 
O.  D.— Outside  diameter. 
O.  H.— Open  hearth. 
Oar  (obs.).— Ore. 

Obersteiner  Process. — See  page  118. 
Objective. — Of  a  microscope:  see  page  285. 
Oblique  Fracture.— See  page  179. 
Oblique  Illumination. — See  page  285 
Oblique  Stress.— See  page  332. 
Oblique  System.— Of  crystallization:  see  page  120 
Obstruction  Theory.— See  page  341. 
Obstructive  Elements.— See  page  276. 

Occlusion.— The  property  possessed  by  certain  metals,  such  as 
iron,    platinum,    and    notably   palladium,    of    absorbing  large 
quantities  of  a  gas  when  heated,  and  retaining  it  when  cold 
(Newth);  see  also  page  328. 
Ochre. — See  page  244. 
Octahedral  Cleavage. — See  page  124. 
Octahedrite. — See  page  291. 
Octaves,  Law  of.— See  page  85. 
Odd-side  Board.— See  page  297. 
Off.— (i)  To  be  through  operating,  or  not  operating;  (2)  to  have 

the  wrong  composition,  e.g.,  to  be  off  in  carbon. 
Off  the  Boil.— See  page  314. 
Off  Iron.— Pig  iron  of  a  different  grade  from  that  intended  to  be 

made. 

Oil  Cooling. — See  page  227. 
Oil  Finish.— See  page  433. 
Oil  Flaring.— See  page  231. 
Oil  Furnace.— See  page  181. 

Oil  Gas.— This  is  obtained  by  the  splitting  up  of  a  hydrocarbon 
oil  at  a  high  temperature,  with  or  without  the  use  of  air  or 
steam,  into  a  permanent  gas.  It  is  used  almost  exclusively  for 
lighting  as  its  cost  of  production  is  too  great  for  metallurgical 
purposes.  Water  oil  gas  (devised  by  Archer)  is  made  as  follows : 
Steam  superheated  to  about  1000°  F.  (550°  C.)  is  made  to  pass 
through  an  injector  and  draw  with  it  a  quantity  of  oil  which 
becomes  mixed  with  the  steam.  The  mixture  is  further  heated 
to  about  1300  F.  (700°  C.),  when  it  receives  an  additional  quan- 
tity of  oil;  and  finally  the  mixture  is  heated  to  2400°  F.  (1300°  C  ) 
whereby  it  is  converted  into  permanent  gas."  Pintsch  gas 
among  others,  is  made  by  dropping  oil  into  a  red-hot  retort' 
somewhat  on  the  principle  of  a  "flash"  boiler,  which  splits  it  up 
into  a  permanent  gas.  Air  gas  is  the  combustible  mixture  of  air 
and  hydrocarbons  obtained  when  ordinary  air  is  passed  through 
the  more  volatile  (liquid)  constituents  of  petroleum.  The 


OIL  GAS  PRODUCER— OPEN  HEARTH  PROCESS      309 

Amet-Ensign  oil  gas  producer  is  used  in  California  where  the 
oil  has  an  asphalt  base,  so  it  is  generally  used  only  under  steam 
boilers.  The  oil  is  fed  in  from  a  weir  box  provided  with  an 
adjustable  needle  .valve  and  runs  down  an  adjacent  inclined 
slide  or  plate,  while  the  air  comes  up  from  below  and  passes  under 
the  lower  edge.  The  products  of  combustion  and  distillation 
there  formed  pass  up  through  a  brick-lined  combining  tube  and 
thence  down  to  a  water  seal,  after  passing  which  they  enter  a 
rotary  washer.  Steam  is  to  be  used  in  the  more  recent  forms 
(Iron  Age,  July  13,  1911). 

Oil  Gas  Producer. — See  Oil  Gas. 

Oil  Hardening;  Quenching;  Tempering.— See  pages  227  and  228. 

Oil  Toughening. — See  page  232. 

Oil  of  Vitriol. — Commercial  sulphuric  acid. 

Oily  Liquid. — See  page  121. 

Old  European  Process. — For  malleable  castings:  see  page  258. 

Old  High  Bloomary. — See  page  147. 

Ologist  Ore. — See  page  244. 

On. — To  be  operating. 

On  the  Boil. — See  page  314. 

On  Gas. — See  page  34. 

On  Wind. — See  page  34. 

Onchnoid. — See  page  290. 

Oncosimeter. — See  page  483. 

One-blow  Test. — See  page  482. 

Onion  (Onion  Skin)  Type. — Of  freezing:  see  page  55. 

Onions  Process. — See  page  118. 

Oolitic  Hematite ;  Ore. — See  page  244. 

Oolitic  Structure. — See  page  125. 

Open. — Of  the  charge  in  a  blast  furnace:  see  page  35. 

Open  Annealing. — See  page  431. 

Open  Fire. — See  page  75. 

Open  Fore-part. — See  page  32. 

Open  Front. — See  page  32. 

Open  Grained  Iron;  Pig. — Pig  iron  whose  fracture  shows  large 
grains  or  crystals. 

Open  Hearth. — See  pages  75  and  182. 

Open  Hearth  Basic  Pig. — See  page  343. 

Open  Hearth  Furnace. — See  pages  183  and  310. 

Open  Hearth  Process. — A  process  for  the  production  of  steel  by 
the  oxidation  and  removal  of  the  impurities  contained  in  a  bath 
of  metallic  iron  lying  on  the  hearth  of  a  regenerative  furnace 
(see  page  183),  the -product  being  tapped  in  a  fluid  condition. 
The  charge  may  consist  of  (0)  pig  iron  (either  solid  or  molten) ; 
(&)  pig  iron  and  scrap;  or  (c)  scrap  and  carbon  (coal  or  coke). 
There  are  two  modifications,  depending  upon  the  nature  of  the 
lining  of  the  furnace : 

1.  Acid  open  hearth  process,  with  removal  of  silicon,  man- 
ganese, and  carbon. 

2.  Basic  open  hearth  process,  with  removal  of  silicon,  manga- 
nese, and  carbon,  as  in  the  acid  process,  and  in  addition  most  of 
the  phosphorus  and  often  some  of  the  sulphur. 


3 1  o  OPEN  HEARTH  PROCESS 

The  original  method  (acid)  of  C.  W.  Siemens  was  to  melt 
pig  iron  alone,  and  oxidize  the  impurities  with  ore  (Siemens 
process,  pig  and  ore  process),  while  the  Brothers  Martin  added 
scrap  without  ore  to  molten  pig  iron  until  the  bath  had  the  right 
composition,  there  being  only  slight  oxidation  from  the  gases 
(Siemens-Martin  process,  Martin-Siemens  process,  Martin 
process,  pig  and  scrap  process),  consequently  the  former  was  an 
oxidation  process  while  the  latter  was  principally  a  dilution 
process.  These  various  names  have,  however,  lost  their  signifi- 
cance and  are  used  interchangeably,  the  terms  pig  and  ore  or  pig 
and  scrap  being  employed  where  it  is  necessary  to  distinguish 
between  them.  Ordinarily  a  combination  method  employing 
pig,  scrap,  and  ore  is  practised.  In  this  country  the  name 
open  hearth  process  is  used  on  account  of  the  type  of  furnace. 
The  name  neutral  Siemens  process  has  been  applied  where  only 
pig  and  scrap  (without  any  ore)  are  used.  The  terms  ordinary 
or  straight  open  hearth  process  are  employed  to  distinguish 
regular  practice  from  special  methods  or  modifications  as  de- 
scribed below. 

Open  Hearth  Furnace. — This  is  a  regenerative  reverberatory 
furnace,  the  name  being  derived  from  the  fact  that  the  hearth 
is  open  or  exposed  to  the  action  of  the  flame.  It  should  more 
properly  be  termed  a  Siemens  furnace  or  Siemens  regenerative 


FIG.  44. — 6o-ton  open  hearth  furnace. 

furnace;  the  term  Martin  furnace  (used  on  the  Continent) 
is  incorrect  as  the  Martins  had  nothing  to  do  with  the  design 
of  the  furnace — only  with  the  process.  The  furnace  com- 
prises a  hearth  or  sole  which  contains  the  charge,  covered  with 
an  arched  roof  of  bricks;  ports  or  passages  at  each  end,  the  air 
and  gas  for  combustion  entering  at  one  end  and  leaving  at  the 
other;  regenerators  (regenerative  chambers)  at  each  end, 
connected  with  the  ports  by  vertical  flues  (uptakes),  and  lead- 
ng  to  the  chimney  or  stack;  at  the  bottom  of  the  uptakes  are 


OPEN  HEARTH  PROCESS 


small  chambers  or  receptacles  (cinder  pockets,  slag  pockets, 
or  dirt  pockets),  easily  cleaned,  for  the  purpose  of  catching  -any 
particles  of  cinder  or  dirt  carried  over,  so  as  to  protect  the 
checkers.  The  hearth  consists  usually  of  metal  plates  lined 
with  silica  bricks,  on  top  of  which  is  the  lining  proper,  consist- 
ing (a)  for  acid  practice,  of  silica  bricks  covered  with  fine  sand; 
(b)  for  basic  practice,  of  magnesite  bricks  covered  with  crushed 
dolomite,  sometimes  mixed  with  a  little  pitch  or  tar.  The  roof 
and  walls  above  where  the  slag  of  the  charge  comes  (slag  line) 
are  built  of  silica  (rarely  magnesite)  bricks,  and  below  this  of 
silica  (acid)  or  magnesite  (basic)  bricks,  depending  upon  the 
process.  Sometimes  chrome  (neutral)  bricks  are  inserted 


FIG.  45. — Model  of  a  50-ton  open  hearth  furnace. 

between  silica  and  magnesite  bricks.  The  hearth  is  provided  at 
the  back  with  a  tap  hole  which,  in  the  case  of  stationary  furnaces, 
must  be  stopped  up  carefully  with  refractory  material;  with  a 
tilting  furnace,  except,  when  tapping,  it  is  above  the  level  of  the 
bath,  and  so  need  not  be  closed  up  tightly.  The  hearth  is  usually 
rectangular  in  shape,  rarely  round  or  oval.  The  regenerators 
are  the  distinctive  feature  of  the  furnace  and  consist  of  fire-brick 
flues  nearly  filled  with  bricks  set  on  edge  and  arranged  so  as  to 
leave  a  great  number  of  small  passages,  known  as  checkers  or 
checker  work,  which  abstract  most  of  the  heat  from  the  out- 
going waste  gases  and  return  it  later  to  the  incoming  (cold)  gases 


312 


OPEN  HEARTH  PROCESS 


for  combustion.  If  producer  gas  is  used,  both  the  air  and  gas 
are  preheated  in  separate  regenerators,  uniting  and  burning  only 
when  they  enter  the  furnace;  with  natural  gas  or  petroleum, 
only  the  air  is  preheated. 

Furnaces  may  be  built  either  on  a  permanent  foundation 
(stationary  or  fixed  furnace),  or  so  arranged  that  the  part  com- 
prising the  hearth  may  be  tipped  (tilting,  tipping,  or  rolling 
furnace).  The  first  type  of  furnace  had  vertical  regenerators 
(i.e.,  the  greatest  dimension  was  vertical),  which  necessitated 
having  the  hearth  and  the  charging  floor  considerably  elevated 
above  the  ground  level;  the  present  practice  is  to  make  the 
regenerators  horizontal,  as  this  lowers  the  charging  floor  which 
can  then  be  on  the  ground  level,  and  also  offers  certain  other 

It  is  now  considered  best  to  have 
a  12"roof  through-out 

H — «' " 

Daubed  with  chrome  cement  - 


2  Courses  magnesia  brick  on  edge/  Granite  or  concrete     //  Loam,  fettling  etc.     N\ 

1  Course  chrome          „      „     .,  ThJSe  checkers  are.not  i/the  These  checker  brick 

uptake,  but  in  a  chamber  just  rest  on  tile  8"x  12 'i  6" 

beyond  and  opening  into  it 

FIG.  46. — Materials    of    construction    and   lining   for   basic    open 
hearth  furnace.     (Stoughton,  Met.  of  Steel.) 

advantages.  One  disadvantage  of  this  latter  arrangement  is 
that  the  pit  at  the  back  of  the  furnace  which  holds  the  ladle  for 
the  steel,  and  the  slag  which  runs  over  (cinder  pit,  slag  pit,  or 
ladle  pit)  must  be  correspondingly  deep,  and  therefore  difficult 
to  clean  on  account  of  the  heat.  To  overcome  this  difficulty, 
the  ground  at  the  back  of  the  furnace  may  be  dug  away,  making 
the  cinder  pit  very  shallow.  This  type  of  construction,  is  called 
a  double  level  furnace ;  the  old  style,  a  single  level  furnace. 
In  the  first  furnaces  the  hearth  was  supported  on  the  regen- 
erator arches  which  were  weakened  by  the  high  temperature 
to  which  they  were  exposed;  also  any  charge  breaking  through 
the  bottom  would  choke  them  up.  This  is  avoided  by  the  use 
of  horizontal  regenerators  which  are  not  underneath  the  hearth ; 
it  was  also  avoided  in  a  special  type  of  furnace,  called  the  Batho 
furnace,  in  which  the  vertical  regenerators  were  inclosed  in  an 


OPEN  HEARTH  PROCESS  313 

iron  sheathing,  being  set  to  one  side  and  independent  of  the 
furnace.  This  furnace  had  a  round  (sometimes  an  oval  or 
elliptical)  hearth,  and  the  roof  was  set  in  an  iron  frame  so  ar- 
ranged that  it  could  be  lifted  off  to  permit  of  charging  scrap  too 
large  to  pass  through  the  regular  charging  doors,  originally 
intended  to  facilitate  repairs  and  relining.  Such  a  furnace  is 
termed  a  removable  top  furnace  (sometimes  a  round  top  furnace), 
a  few  of  which  are  still  employed. 

In  this  country  furnaces  used  in  connection  with  the  manu- 
facture of  ingots  generally  have  a  capacity  per  charge  of  about 
50  to  100  tons;  for  some  special  processes,  up  to  200  tons  or 
over,  and  in  this  case  are  usually  tilting.  Smaller  furnaces, 
about  10  to  20  tons  in  size,  are  generally  confined  to  the  manu- 
facture of  steel  for  castings.  With  ordinary  practice,  a  heat 
takes  from  about  6  to  12  hours,  usually  8  to  10  hours,  and  a 
furnace  will  make  about  12  to  22  heats  per  week,  depending  upon 
the  size  (less  for  large  than  for  small). 


FIG.  47. — 6o-ton  open  hearth  furnace,  showing  charging  machine 
and  charging  boxes. 

With  a  newly  built  furnace,  before  it  can  be  used  for  making 
steel,  the  first  operation  is  making  bottom,  i.e.,  putting  in  the 
lining.  Gas  is  burned  to  warm  up  the  hearth  and  the  checkers 
until  the  full  working  temperature  is  reached.  With  proper 
construction  a  sufficiently  high  temperature  to  fuse  the  roof 
can  be  attained.  The  refractory  lining  is  then  put  on  in  thin 
layers,  each  of  which  is  sintered  in  place  before  the  next  is  put 
on.  With  an  acid  furnace  a  certain  amount  of  old  slag  is  then 
thrown  in,  melted,  and  tapped  out.  This  is  called  a  wash 
heat  or  wash  out  heat  and  is  for  the  purpose  of  making  the 
bottom  dense  and  firm.  The  furnaces  were  originally  charged 
by  hand,  the  materials  being  laid  on  a  peel  (a  bar  flattened  out 
at  one  end  like  a  spade)  which  was  rested  on  the  sill  of  one  of 
the  doors  as  a  fulcrum,  and  so  pushed  in  (peel  charging);  but 
with  modern  large  furnaces,  both  on  account  of  the  time  required 


3 1 4  OPEN  HEARTH  PROCESS 

and  the  arduousness  of  the  labor,  this  is  done  by  a  machine 
(charging  machine).  The  stock  is  loaded  into  boxes  (charging 
boxes)  which  are  picked  up  by  the  machine  and  dumped  in  the 
furnace  by  revolving  the  peel  of  the  machine  which  engages  with 
them  at  one  end. 

Acid  Open  Hearth  Process. — Ordinarily  the  charge  is  com- 
posed of  pig  and  scrap,  the  scrap  as  a  rule  constituting  the  greater 
part.  The  materials  must  contain  less  phosphorus  (0.06%) 
than  is  to  appear  in  the  finished  steel  (see  page  343).  In  some 
cases  the  scrap  is  charged  first,  with  the  pig  on  top,  in  others 
this  order  is  reversed,  the  object  being  to  prevent  scorification  of 
the  lining  by  the  iron  oxide  formed  during  melting.  The  first 
stage  consists  in  melting  the  materials  down,  during  which  much 
of  the  silicon,  manganese,  and  carbon  are  oxidized.  When 
completely  melted,  the  bath  should  contain  about  0.60%  of 
carbon  if  low-carbon  steel  is  to  be  made,  or  over  i  %  for  high- 
carbon  steel  for  springs,  etc.  To  determine  this,  a  sample  is 
taken  out  in  a  spoon  and  poured  into  a  small  mold,  the  test 
ingot  resulting  being  chilled  in  water  and  broken,  its  fracture 
giving  the  desired  information.  Frequently  with  high-carbon 
steel  a  quick  chemical  determination  is  also  made.  If  the  heat 
melts  high,  i.e.,  if  the  carbon  is  still  too  high,  ore  in  small  amounts 
can  be  fed  in  (oreing  or  oreing  down)  to  effect  the  oxidation, 
without  danger  of  corroding  the  lining,  as  this  is  now  protected 
by  the  metallic  bath  and  the  slag  already  formed;  if  the  heat 
melts  low,  with  the  danger  of  the  bath  not  getting  hot  enough  by 
the  time  the  carbon  is  nearly  all  gone,  pig  is  thrown  in  to  supply 
the  deficiency  in  carbon,  and  this  is  termed  pigging,  pigging  back, 
or  pigging  up.  The  period  after  melting,  when  the  carbon  is 
being  oxidized,  is  sometimes  called  the  boil,  and  the  charge  is  said 
to  be  on  the  boil ;  if  nearly  all  the  carbon  has  been  oxidized,  it  is 
off  the  boil.  To  assist  in  oxidizing  the  carbon,  the  bath  may  be 
stirred  (shaken  down)  with  an  iron  rod.  In  some  cases  steel  may 
be  obtained  with  a  higher  percentage  of  silicon  than  usual,  due  to 
a  reaction  or  sand  boil  (Eng.)  whereby  silicon  is  reduced  from  the 
bottom  or  banks  of  the  furnace. 

A  certain  amount  of  heat  is  generated  by  the  oxidation  of  the 
impurities,  but  the  greater  part  is  obtained  from  the  combustion 
of  the  gas.  Contact  of  the  iron  with  the  hot  gases  is  principally 
brought  about  by  the  evolution  of  the  carbon  monoxide  gas 
formed  by  the  oxidation  of  the  carbon  in  the  metallic  bath,  which 
causes  it  to  bubble  and  seethe;  consequently  it  is  necessary  to 
have  a  certain  amount  of  carbon  in  the  bath,  as  otherwise  it  will 
be  too  cold  to  tap.  The  temperature  of  the  bath  is  determined 
partly  by  the  eye  and  partly  from  the  effect  on  a  low-carbon  iron 
bar  in  about  ten  seconds.  If  the  bar  is  melted  off  sharply  the 
bath  is  sufficiently  hot,  while  if  it  tapers  to  a  point  it  is  too  cold. 
The  direction  of  the  air  and  the  gas  for  combustion  is  reversed 
at  regular  intervals:  about  20  minutes  at  the  beginning  and  15 
minutes  or  less  toward  the  end  of  the  heat. 

Just  before  tapping,  a  small  amount  of  ferro-manganese  is 
usually  thrown  into  the  furnace  to  hold  the  heat,  i.e.,  to  prevent 


OPEN  HEARTH  PROCESS  3 1 5 

any  further  removal  of  carbon,  and  also  to  effect  a  partial  de- 
oxidation  of  the  bath.  There  are  two  methods  for  obtaining 
the  right  carbon  content:  (a)  by  removing  practically  all  the 
carbon  and  then  recarburizing;  (6)  by  tapping  when  the  carbon 
has  been  reduced  to  the  right  percentage  (catching  the  carbon  on 
the  way  down).  In  either  case  manganese  (and  sometimes 
silicon)  must  be  added  (generally  in  the  ladle)  to  remove  the 
remaining  oxide  in  the  metal.  When  the  bath  is  in  the  right 
:  ondition  as  regards  both  composition  and  temperature,  it 
is  run  out  of  the  furnace  (tapped)  by  knocking  out  the  material 
in  the  tapping  hole,  if  a  stationary  furnace,  or,  if  a  tilting  fur- 
nace, by  lowering  the  tapping  hole  so  the  metal  will  flow  out. 
It  is  caught  in  a  ladle,  and  poured  into  molds.  Recarburization 
(q.v.)  is  usually  performed  in  the  ladle,  but  may  also  be  done  in 
the  furnace  before  tapping.  Instead  of  tapping  into  a  ladle, 
from  which  the  molds  are  filled,  the  steel  may  be  run  into  a 
fore  hearth,  a  small  chamber  or  tank  attached  to  the  furnace, 
and  provided  with  holes  in  the  bottom  for  filling  the  molds :  its 
object  is  to  prevent  chilling  of  the  metal.  Occasionally,  after 
tapping,  some  of  the  steel  sticks  around  the  tapping  hole,  and  is 
sometimes  termed  a  dog  collar.  A  chestnut  is  a  lump  of  steel 
sticking  in  the  tapping  hole. 

Basic  Open  Hearth  Process. — As  in  the  acid  process,  the 
charge  usually  consists  of  pig  iron  (preferably  molten)  and  scrap 
(with  ore  and  limestone  in  addition),  but  the  materials  are 
not  restricted  as  regards  the  phosphorus  content;  the  sulphur, 
however,  should  be  low,  as  its  elimination  is  very  uncertain, 
and  at  most  slight;  the  silicon  should  also  be  low,  to  avoid 
the  use  of  an  excessive  amount  of  lime.  Since  the  lining  is 
basic,  ore  can  be  charged  initially  without  the  danger  of  injuring 
it.  The  actual  elimination  of  the  phosphorus  is  performed 
by  the  lime,  usually  added  as  limestone,  but  occasionally  burned 
beforehand.  With  these  differences  the  basic  process  closely 
resembles  the  acid  as  regards  melting  and  the  preparation  of 
the  bath.  The  proportion  of  pig  is  generally  larger,  and  when- 
ever practicable  it  is  charged  in  the  molten  condition,  as  a  mate- 
rial saving  in  time  and  cost  of  handling  results. 

Under  a  superintendent  a  foreman  has  charge  of  a  number 
of  furnaces  and  is  responsible  for  the  composition  and  the  condi- 
tion of  the  steel  produced.  The  individual  furnaces  are  operated 
by  a  melter  or  first  helper,  an  assistant  melter  or  second  helper, 
and  a  cinder  pitman,  the  last  named  cleaning  out  the  cinder  pit, 
and  assisting  the  others  in  fettling  the  furnace,  i.e.,  repairing  the 
lining.  There  is  also  the  gang  necessary  to  load  the  stock, 
prepare  the  ladles,  pour  the  heats,  etc. 

Special  open  hearth  processes  are  modifications  of  ordinary 
practice  designed  to  decrease  cost,  increase  output,  or  make  use 
of  material  of  troublesome  composition  (e.g.,  high  phosphorus  or 
high  silicon).  The  most  important  are  the  following: 

Bertrand-Thiel  process:  This  was  designed  especially  for 
the  use  of  pig  when  the  phosphorus  is  too  high  (about  i  to  2%) 
to  be  treated  in  ordinary  open  hearth  practice  on  account  of  the 


3 1 6  OPEN  HEARTH  PROCESS 

bulky  slag  required,  but  too  low  for  the  basic  Bessemer  process. 
It  consists  in  charging  pig,  either  alone  or  mixed  with  scrap, 
together  with  ore  and  lime,  in  one  basic  furnace  (primary  furnace, 
finer,  or  refiner)  in  which  nearly  all  the  phosphorus  and  silicon 
and  only  a  small  part  of  the  carbon  are  removed,  the  resulting, 
partly  purified  metal,  without  any  of  the  slag,  being  then  trans- 
ferred to  another  basic  furnace  (secondary  furnace  or  finisher)  in 
which  scrap,  or  ore,  or  both,  together  with  some  lime  (occasion- 
ally also  a  little  pig)  have  previously  been  heated,  when  a  very 
rapid  reaction  takes  place  between  the  iron  oxide  formed  and  the 
remaining  impurities  in  the  metal,  which  are  quickly  reduced 
to  below  the  required  limits.  The  further  details  are  the  same  as 
in  regular  practice.  The  time  required  is  about  two  to  four 
hours  in  each  furnace. 

Monell  process:  This  is  a  modification  of  the  pig  and  ore 
process  Ahich,  however,  may  also  employ  scrap.  It  is  ordi- 
narily carried  out  in  a  fixed  basic  furnace,  but  a  tilting  furnace 
will  also  serve.  It  consists  in  heating  limestone  and  ore  or  some 
form  of  iron  oxide,  the  latter  amounting  to  about  20  to  25  %  of  the 
weight  of  the  pig,  until  it  becomes  pasty,  when  the  pig,  in  a 
molten  condition,  is  run  in,  and  a  violent  reaction  takes  place. 
A  large  amount  of  slag  is  formed  which  is  run  out  of  a  special 
notch  into  an  auxiliary  cinder  pit  (hunch  pit),  if  a  fixed  furnace 
is  used,  or  out  of  the  tapping  hole,  in  the  case  of  a  tilting  furnace, 
by  tilting  it  slightly.  This  slag  contains  about  90  %  of  the  phos- 
phorus and  most  of  the  silicon  originally  in  the  pig,  about  2% 
of  carbon  being  still  left  in  the  bath.  The  heat  is  then  worked 
down  and  handled  as  in  regular  practice  taking  about  the  same 
total  time  as  an  ordinary  pig  and  scrap  heat. 

Talbot  process  or  Talbot  continuous  process:  This  is  a  pig 
and  ore  process  although  scrap  is  occasionally  added.  It  depends 
upon  the  rapid  oxidation  of  the  impurities  contained  in  pig  iron  by 
a  liquid,  highly  ferruginous  slag,' and  is  carried  out  in  a  basic  open 
hearth  furnace,  generally  of  the  tilting  type.  The  essential  feature 
of  the  process  is  always  keeping  a  certain  amount  of  metal  in  the 
furnace  (a)  to  dilute  the  impurities  contained  in  the  additions  of 
pig  iron,  and  (b)  to  supply  the  heat  necessary  to  keep  the  slag 
very  fluid.  A  tilting  furnace  of  200  tons  capacity  or  over  is 
ordinarily  employed,  and  from  about  one-quarter  to  one-third  of 
the  finished  steel  is  tapped  out  at  one  time.  This  having  been 
done,  additions  of  ore  or  iron  oxide  and  lime  are  made,  and  after 
they  are  properly  melted  and  incorporated  in  the  slag,  molten 
pig  iron  is  run  in  and  a  violent  reaction  takes  place,  most  of  the 
phosphorus  and  silicon  being  eliminated  in  a  few  minutes,  a  large 
part  of  the  slag  running  out  of  the  furnace.  The  bath  is  then  ad- 
justed as  in  ordinary  practice,  a  part  tapped,  and  the  cycle  of 
operations  repeated.  A  furnace  is  emptied  completely  only  at 
the  end  of  the  week  or  for  repairs.  The  name  Talbot  furnace  is 
applied  to  an  open  hearth  furnace  in  which  this  process  is  con- 
ducted, but  is  really  incorrect  as  the  process  does  not  require 
any  special  type.  A  heat  can  be  made  in  about  three  to  four 


OPEN  HEARTH  PROCESS  3 1 7 

hours.  This  process  is  sometimes  run  in  conjunction  with  the 
duplex  process  (see  below) . 

Surzycki  process :  This  is  the  Talbot  process  carried  out  in 
a  stationary  open  hearth  furnace,  with  tapping  holes  at  different 
heights  for  permitting  the  removal  of  the  slag  and  portions  of  the 
metal. 

Campbell  processes :  These  are  two  modifications  of  the  open 
hearth  process.  The  first  is  simply  a  pig  and  ore  process  with 
molten  metal,  and  employing  a  tilting  furnace  of  the  Campbell 
type.  The  foamy  slag  produced  early  in  the  process  is  prevented 
from  running  out  of  the  doors  by  properly  tilting  the  furnace. 
Any  excess  is  allowed  to  run  out  through  a  slag  notch  between  the 
end  of  the  furnace  and  the  port  which  is  prevented  from  chilling  by 
the  flame  constantly  passing  over  it.  After  the  foaming  has 
subsided  the  furnace  is  restored  to  its  normal  position  and  the  heat 
finished  as  usual.  In  the  second  modification  the  heat  is  com- 
menced in  a  basic  furnace,  run  at  a  low  temperature^at  which 
most  of  the  phosphorus  and  silicon,  and  some  of  the  carbon, 
manganese,  and  sulphur,  are  removed.  The  charge  is  then  trans- 
ferred to  an  acid  furnace,  and  finished  as  usual,  care  being  taken 
to  prevent,  any  of  the  basic  slag  from  running  in  with  the  metal. 
The  initial  charge  may  be  constituted  in  various  ways.  The 
object  is  to  obtain  any  benefits  supposed  to  accrue  to  acid  steel. 

Duplex  process:  This  was  designed  for  the  use  of  ordinary 
materials,  but  more  especially  for  the  use  of  pig  iron  high  in 
phosphorus  and  silicon.  It  consists  in  first  blowing  the  molten 
pig  iron  in  an  acid  Bessemer  converter  to  remove  the  silicon 
and  varying  proportions  of  the  carbon,  the  blown  metal  being 
transferred  to,  and  finished  in,  a  basic  open  hearth  furnace 
(frequently  tilting)  according  to  regular  practice.  The  blow- 
ing takes  about  ten  to  fifteen  minutes  and  the  finishing  in  the 
open  hearth  furnace  from  two  to  eight  hours,  depending  upon 
the  size  of  the  furnace  and  certain  other  conditions. 

The  following  processes  are  of  only  general  interest : 

Berard  process:  Two  furnaces  were  used,  joined  together, 
and  heated  by  gas.  In  one  hearth  air  was  blown  into  the  bath 
through  tubes  dipping  beneath  the  surface  and,  after  being 
sufficiently  refined,  the  charge  was  transferred  to  the  other 
hearth  and  finished. 

Biederman  and  Harvey's  modification  consisted  in  return- 
ing a  part  of  the  waste  gases  through  the  producer  (a)  to  make 
use  of  their  sensible  heat  and  (6)  to  obtain  a  gas  containing  less 
nitrogen  than  when  air  alone  is  employed. 

In  Bouiniard's  process  a  jet  of  air  was  used  to  stir  up  the 
metal  in  much  the  same  way  as  adopted  by  Ponsard. 

In  the  Daelen-Pszczolka  process  hot  air,  under  low  pressure, 
is  blown  on  the  surface  of  the  bath.  • 

Dyer's  process  consists  in  melting  scrap  with  carbonaceous 
material  instead  of  with  pig  iron*, 

M.  Ehrenwerth  and  J.  Rrochaska's  process  consisted  in 
employing  briquettes  of  ore,  charcoal  or  coke,  and  pig  iron 
which  were  to  be  charged  in  place  of  scrap.  The  ore  and  char- 


3 1 8  OPEN  HEARTH  PROCESS 

coal  were  either  placed  in  a  mold,  and  molten  pig  iron  run  in, 
or  else  were  made  into  bricks  around  which  the  pig  iron  was  cast. 

P.  Eyerman's  process  consists  (a)  in  employing  blast  furnace 
gas  which  is  passed  over  heated  carbon  to  convert  the  carbon 
dioxide  into  carbon  monoxide,  and  (6)  in  directing  a  jet  of  air 
upon  the  bath. 

Galy-Cazalet's  process  was  an  old  method  for  refining  pig 
and  making  steel  by  injecting  steam  through  the  molten  metal 
contained  in  a  cylindrical  furnace,  provided  with  several  tuyeres, 
or  in  an  ordinary  reverberatory  furnace.  It  was  not  a  success, 
as  the  cooling  effect  of  the  steam  was  too  great. 

P.  C.  Gilchrist's  process  consists  in  melting  pig  and  lime  in  a 
basic  furnace,  the  amount  of  lime  being  less  than  ordinarily  re- 
quired. At  the  same  time  a  charge  is  blown  in  a  basic  Bessemer 
converter  with  an  excess  of  lime,  and  this  molten  scrap  together 
with  the  slag  is  added  to  the  now  molten  charge  in  the  open  hearth 
furnace,  and  the  heat  finished  as  usual. 

W.  B.  Hughes'  process  was  essentially  a  modification  of  the 
Monell,  and  consisted  in  adding  a  suitable  slag  of  iron  ore  and 
lime  in  a  molten  condition  after  preparing  it  in  a  separate  furnace. 

In  Krupp's  process  a  furnace  on  the  same  principle  as  a 
Ponsard  furnace  was  used.  It  had  a  revolving  hearth  slightly 
inclined  to  the  horizontal  and  with  tuyeres  at  one  part.  When 
these  were  at  the  lowest  point  they  blew  air  through  the  bath, 
but  at  the  highest  point  they  were  above  the  bath  and  the  air 
was  stopped. 

In  the  Lencauchez  process  the  charge  of  pig  or  pig  and  scrap 
is  held  molten  at  a  low  temperature  to  effect  separation  of  the 
manganese  sulphide,  after  which  the  temperature  is  slightly 
raised  (but  not  to  the  point  where  the  carbon  is  attacked), 
and  air  is  blown  on  the  surface  to  effect  the  oxidation  of  the 
phosphorus  and  silicon;  ore  or  scale  may  also  be  used  for  this 
purpose.  The  charge  may  be  finished  in  the  same  or  in  another 
furnace. 

In  the  Lindenthal  process  pig  iron  is  melted  in  a  cupola  and 
run  down  through  a  closed  conduit  into  a  receiver.  During 
its  passage  jets  of  air  are  blown  on  it  to  oxidize  the  silicon  and 
phosphorus.  From  the  tank  furnace  the  metal  (without  any 
slag)  is  run  into  a  basic  open  hearth  furnace  and  finished  as  usual. 

NivenMcConnell's  process  was  to  desiliconize  the  pig  iron  in  an 
acid  converter,  at  the  same  time  reducing  the  carbon  to  about  i  %. 
This  metal  was  then  transferred  to  a  heated  mixer  from  which 
portions  were  taken  periodically  and  finished  in  a  basic  open 
hearth  furnace  as  usual. 

Parry  and  Llewellyn's  process:  Pig  and  ore,  etc.,  are  charged 
in  alternate  layers  and  are  heated  just  sufficiently  to  melt  the 
slag  which  is  allowed  to  run  off;  the  temperature  is  then  raised 
to  melt  the  metal.  The  operation  may  be  carried  out  in  a 
furnace  with  one  or  two  hearths. 

The  Ponsard  process  consists  in  using  a  special  furnace 
known  as  a  Ponsard  furnace  or  Fornoconvertisseur  having 
a  movable  hearth  and  heated  with  gas.  It  is  provided  with 


OPEN  HEARTH  PROCESS— OPTIMUM  3 1 9 

tuyeres  so  that  air  can  be  blown  through  the  metal  during  the 
earlier  stages,  and  then,  by  partially  revolving  the  hearth,  the 
tuyeres  are  disconnected  from  the  bath,  and  the  process  carried 
on  in  the  same  way  as  in  an  ordinary  open  hearth  furnace. 
Another  method  was  to  use  a  hollow,  water-cooled  poker  through 
which  air  was  blown  into  the  bath  to  stir  it  up. 

In  the  Schwartz  process  a  large  proportion  of  the  charge  is  steel 
scrap  which  is  melted  in  a  cupola  and  run  into  a  bath  of  .pig  iron 
in  a  special  type  of  furnace;  it  was  claimed  to  be  very  rapid. 

J.  W.  Thomas'  process  was  devised  for  the  manufacture  of 
steel  direct  from  titaniferous  ores.  After  crushing  they  were 
mixed  with  coal,  coke,  or  charcoal,  2%  of  lime,  and  i%  of  salt, 
and  were  molded  into  briquettes  which  were  added  to  a  bath 
of  pig  iron  in  an  open  hearth  furnace,  and  the  heat  finished 
as  usual.  The  ore  added  in  this  way  amounted  to  about  40%  of 
the  weight  of  pig  iron. 

The  Twynam  process  consists  in  adding  a  certain  quantity 
of  briquettes,  composed  of  iron  ore  and  carbon,  to  the  bath  of 
a  basic  open  hearth  furnace;  it  was  claimed  that  the  reduction 
of  the  iron  was  very  complete,  but  the  process  was  used  only 
experimentally. 

Wurtemberger's  process  was  designed  to  hasten  operations 
by  blowing  air  into  the  bath  after  the  charge  had  melted  down. 
Air  under  a  pressure  of  7  to  8  pounds  was  introduced  through  i" 
tuyeres,  protected  by  clay,  which  were  dipped  into  the  bath. 
It  was  found,  however,  that  the  lining  of  the  furnace  was 
destroyed  to  such  an  extent  that  the  gain  in  the  actual  process 
was  more  than  lost  by  the  time  required  for  repairs. 

Wuth's  process:  The  charge  in  an  open  hearth  furnace  was 
composed  of  alternate  layers  of  bar  iron  (wrought  iron)  and 
graphite  and  was  treated  in  the  ordinary  manner,  spiegel  or 
ferro-manganese  being  added  at  the  end  of  the  heat. 

Open  Hearth  Processes,  Special. — See  page  315. 

Open  Hearth  Steel. — Steel  made  by  the  open  hearth  process  (see 
above)  either  acid  or  basic. 

Open  Iron. — See  page  343. 

Open  Order  En  Echelon. — See  page  283. 

Open  Pass. — See  page  405. 

Open  Pit. — See  page  57. 

Open  Sand  Castings. — See  page  57. 

Open  Sand  Mold. — See  page  299. 

Open  Sea. — In  the  freezing  of  alloys:  see  page  54. 

Open  Spray  Tuyere. — See  page  31. 

Open  Steel. — See  page  55. 

Open  Top. — Of  a  blast  furnace:  see  page  34. 

Open  Top  Mold. — See  page  299. 

Open  Tuyere.— See  page  32. 

Opposition  Method.— See  page  209. 

Optical  Analysis.— See  page  284. 

Optical  Pyrometer. — See  page  207. 

Optimum  (rare). — Best;  e.g.,  optimum  temperature  means  the  best 
or  most  favorable  for  a  given  reaction  or  condition. 


3  20  ORANGE  HEAT— ORE 

Orange  Heat. — See  page  210. 

Ordinary  Annealing. — See  page  231. 

Ordinary  English  Pig  Irons. — See  page  349. 

Ordinary  Ferro -Silicon. — See  page  354. 

Ordinary  Iron. — Sometimes  applied  to  cast  iron  castings  to  dis- 
tinguish them  from  malleable  castings. 

Ordinary  Line  of  Deformation. — See  page  126. 

Ordinary  Open  Hearth  Process. — See  page  310. 

Ordinary  Solder. — See  page  505. 

Ordinary  Steel. — See  page  443. 

Ordinary  Tool  Steel. — See  page  445. 

Ordinate. — See  Curve. 

Ore. — A  natural  mineral  substance  consisting  of  (a)  one  or  more 
(usually)  metallic  elements,  generally  in  the  combined  state,  and 
(b)  non-metallic  elements  as  impurities  or  diluents,  called  the 
gangue.  It  is  understood  that  there  shall  be  a  sufficient  propor- 
tion of  at  least  one  of  the  metals  to  permit  of  its  commercial 
(profitable)  extraction.  Thus,  a  clay  containing,  say,  6%  of  iron 
would  not  be  considered  as  an  ore  of  iron,  as  the  iron  could  not  be 
recovered  profitably. 

Beneficiation  or  benefaction  is  the  general  term  applied 
to  the  preliminary  treatment  of  an  ore,  having  for  its  object 
either  the  enrichment  of  its  metallic  contents  or  the  removal  of 
injurious  constituents,  either  by  bodily  removal  or  their  change 
into  something  less  harmful.  By  roasting  or  calcination  (q.v.) 
moisture  and  volatile  substances  are  driven  off,  and  carbonaceous 
or  combustible  matter  is  burned  out.  It  is  carried  out,  usually 
with  the  admixture  of  solid  fuel,  in  open  piles,  kilns,  and  some- 
times in  cupolas  or  small  shaft  furnaces,  an  excess  of  air  being 
necessary.  The  removal  of  a  considerable  part  of  the  earthy 
matter  or  gangue  may  be  effected  by  washing  in  a  washer  or  jig, 
by  taking  advantage  of  the  differences  in  the  respective  specific 
gravities.  The  material  is  crushed  and  separated  into  lots, 
consisting  of  pieces  of  nearly  equal  size,  by  suitable  screens 
(sizing),  and  is  put  in  a  jig  or  washer,  the  bottom  of  which  has 
water  pulsating  through  it.  The  material  is  fed  in  at  the  top, 
and  the  quicksand  condition  allows  the  constituents  to  separate 
according  to  their  specific  gravities  (sorting),  and  they  are  then 
drawn  off  through  separate  holes.  Only  pieces  of  the  same  size 
are  treated  together.  The  earliest  type  of  shaft  washer  consisted 
of  a  log  1 6  to  30  feet  long  fitted  with  blades  revolving  in  an  in- 
clined trough,  into  which  the  ore  is  dumped  and  streams  of  water 
added.  As  the  log  revolves,  the  blades  cut  the  clay  lumps  and 
force  the  sand,  gravel  and  the  ore  up  the  incline  of  the  trough  to  a 
discharge  opening,  the  water  carrying  away  the  clay.  This  was 
sometimes  called  a  buddle.  It  was  improved  by  using  two  par- 
allel logs  in  one  trough,  and,  later,  iron  shafts  replaced  the  logs. 
In  cone  washers  there  are  a  series  of  perforated  iron  staves  se- 
cured to  spiders,  forming  a  cylinder  with  a  conical  end,  which  is 
revolved  by  gearing,  into  which  the  ore  is  fed  with  a  stream  of 
water.  The  staves  have  on  their  inner  faces  a  series  of  blades  or 
cutters  which  break  up  the  clay  lumps,  the  water  carrying  this 


ORE  BLOOM— OUTSIDES  321 

off,  and  the  fine  ore  passes  into  a  revolving  screen  which  saves 
all  the  ore  above  a  determined  size  (Birkinbine).  Cobbing 
(Eng.)  is  a  term  used  for  hand  picking.  Magnetic  concentration 
or  separation  consists  in  the  removal  of  nearly  all  the  iron  oxide, 
in  the  form  of  the  magnetic  oxide  (FesOO  by  the  aid  of  powerful 
magnets.  If  it  does  not  already  exist  in  that  condition  a  pre- 
liminary roasting  may  be  necessary  for  its  formation.  This 
treatment  may  be  either  for  the  purpose  of  enriching  an  ore  of 
iron  or  of  removing  iron  when  its  presence  is  undesirable.  The 
finely  crushed  material  may  be  brought  into  contact  with  magnets 
so  the  magnetic  particles  are  removed  on  traveling  belts  or  re- 
volving drums;  another  method  is  to  deflect  these  particles 
when  falling  in  a  stream  past  the  magnet.  Agglomerating  fine 
particles  into  coherent  masses  is  dealt  with  under  Briquette. 

Ore  Bloom. — See  page  135. 

Ore  Bridge. — See  page  32. 

Ore  Burden. — See  page  34. 

Ore  Distributing  Devices. — See  page  32. 

Ore  Metal.— See  page  350. 

Ore  of  Steel. — See  page  245. 

Oreing;  Oreing  Down. — See  page  314. 

Organic;  Chemistry. — See  page  82. 

Orient;  Orientation. — See  page  119. 

Oriented  Lustre. — See  page  127. 

Origin. — In  plotting  curves:  See  Curve. 

Orthobasic. — See  pages  122  and  350. 

Orthorhombic  System. — Of  crystallization:  see  page  120. 

Orthosymmetric  System. — Of  crystallization :  see  page  1 20. 

Orthotomous. — See  page  1 24. 

Orthotypous. — See  page  1 24. 

Orton  Cones. — See  page  209. 

Osborne  Process. — See  page  380. 

Osmond  and  Cartaud's  Method. — Of  etching:  see  page  288. 

Osmond  and  Cartaud's  Theory. — Of  slip  bands:  see  page  283. 

Osmond  Method. — Of  quenching:  see  page  229. 

Osmond's  Reagents. — For  etching:  see  pages  287  and  288. 

Osmond's  Theory. — (i)  Of  the  allotropy  of  iron:  see  page  264; 
(2)  of  hardening:  see  page  279. 

Osmondite. — See  page  277. 

Osmonditic  Martensite. — See  page  276. 

Osmose ;  Osmotic  Pressure. — See  Solution. 

Osmund ;  Osmund  Furnace ;  Process. — See  page  144. 

Ostlund  Process.— See  page  380. 

Ostracoid.— See  page  290. 

Otto  Process. — See  page  144. 

-ous. — Chemical  suffix:  see  page  88. 

Out  of  Wind. — Not  twisted  or  alternately  bent;  a  requirement  in 
some  rail  specifications. 

Output. — The  production  of  a  mill,  plant,  or  company  for  a  certain 
period. 

Outside  Gage.— See  page  186. 

Outsides;  Outside  Sheet.— See  page  431. 
21 


322  OVAL  GROOVE— OXYGENITE  PROCESS 

Oval  Groove;  Pass. — See  page  405. 

Oven. — See  page  181. 

Over  Iron. — Surplus  of  (pig)  iron  melted  for  filling  molds. 

Overblow. — See  page  20. 

Overburdened. — Of  a  blast  furnace:  see  page  34. 

Overcarburization. — See  page  68. 

Overhang. — Of  a  tuyere:  see  page  31. 

Overheating. — See  page  226. 

Overheating  Zone.— See  page  226. 

Overstrain. — See  pages  216  and  334. 

Overstrained  Ferrite. — See  page  216. 

Overstraining. — In  hardening:  see  page  279. 

Overwork. — See  page  99. 

Oxidated  (rare).— Oxidized. 

Oxidation. — See  page  88. 

Oxide. — (i)  The  combination  of  another  element  with  oxygen; 
(2)  oxide  of  iron  or  rust;  (3)  dross;  (4)  sometimes  used  for 
"scale,"  e.g.,  black  oxide. 

Oxide  Bottom. — See  Lining. 

Oxide  Coating. — See  page  362. 

Oxide  Film  Theory. — Of  passivity:  see  page  364. 

Oxide  of  Iron. — See  page  396. 

Oxide  Ore. — See  page  243. 

Oxide  Pearlite. — See  page  274. 

Oxide  Skin  Theory;  Oxide  Theory. — Of  passivity:  see  page  364. 

Oxone. — A  trade  name  for  fused  sodium  peroxide. 

Oxyacetylene  Cutting ;  Welding. — See  page  503. 

Oxygen.— O;  at.  wt.,  16;  melt.  pt.  -223°  C.  (—369°  F.);  boil, 
pt.,  -i82.s°C.  (-296.5°  F.);  sp.  gr.,  1.1056  (air  =  i);  i  liter 
weighs  1.429  grams.  It  is  a  colorless,  odorless,  and  tasteless 
gas,  forming  one-fifth  of  the  air  by  volume,  and  is  found  in 
combination  with  various  elements;  it  combines  with  all  the 
elements  except  fluorine.  Iron  oxide  dissolved  in  iron  makes 
the  metal  both  red-short  and  cold-short;  in  combination  with 
manganese  this  effect  is  not  so  noticeable,  as  the  compound  ap- 
pears to  be  only  mechanically  held.  Ledebur  states  that  iron 
containing  combined  oxygen  up  to  0.10%  can  be  worked,  but 
that  above  this  the  metal  is  bad;  the  maximum  content  is  about 
0.25  to  0.30%.  Uncombined  oxygen  is  sometimes  found 
in  blowholes  or  pockets. 

Oxygen  Charge  Theory. — Of  passivity:  see  page  364. 

Oxygen  Film  Theory  ;  Oxygen  Theory. — Of  passivity:  see  page  364. 

Oxygenated. — Oxidized  or  impregnated  with  oxygen  or  oxide; 
burnt. 

Oxygenated  Steel. — See  page  226. 

Oxyhydrogen  Cutting ;  Welding.— See  page  503. 

Oxygenite  Process. — A  trade  name  for  oxyacetylene  welding :  see 
page  503. 


P. — (i)  Chemical    symbol    for    phosphorus,    q.v. ;    (2)  pressure. 

Pb. — Chemical  symbol  for  lead  (Latin,  plumbum),  q.v. 

Pd. — Chemical  symbol  for  palladium:  see  page  84. 

Pr. — Chemical  symbol  for  praseodymium:  see  page  84. 

Pt. — Chemical  symbol  for  platinum :  see  page  84. 

P.  D. — Pitch  diameter;  used  in  estimating  the  size  of  rolling  mills; 
the  distance  between  the  center  points  of  pinions  and  gears. 

P.  &.  M.  S. — Planished  and  machine  straightened  (of  tires,  etc.). 

P.  &  O.  Process.— Pig  and  ore:  see  page  310. 

P.  &  S.  Process. — Pig  and  scrap :  see  page  310. 

Paal  Steel  Process.— See  page  78. 

Pack. — See  page  430. 

Packard  Motor  Company  Process. — See  page  225. 

Paddle. — A  flat  tool  employed  by  puddlers  in  preparing  the  lining. 

Paddling  Door. — See  Mixer. 

Paint. — See  page  365. 

Pair;  Pair  Furnace. — See  page  430. 

Pallasite. — See  page  292. 

Pallisades  (obs.). — Old  name  for  bars. 

Pallets  (Eng.). — Or  bitts;  the  cast  iron  tools  with  chilled  faces,  used 
in  forging,  which  come  in  contact  with  the  object  to  form  it. 

Pan  (obs.).— Ladle. 

Pane. — Also  spelled  pean,  peen,  pein,  or  pene  ;  it  is  the  striking  face 
or  the  smaller  and  narrower  end  of  a  hammer  head.  It  is  termed 
a  ball  pane  when  it  is  spherical  in  form :  a  cross  pane  when  in  the 
form  of  a  narrow,  round-edged  ridge  placed  at  right  angles  to  the 
axis  of  the  shaft;  a  straight  pane  when  a  ridge  of  the  same  charac- 
ter runs  longitudinally  (Homer). 

Paper  Chill. — See  page  350. 

Parallel  Qrowth. — See  page  121. 

Paramorph. — See  page  122. 

Paris  Gage. — See  page  188. 

Parker  Process. — See  page  369. 

Parkes  Process. — See  page  62. 

Parrot  Coal.— See  Coal. 

Parry  and  Llewellyn  Process. — See  page  318. 

Parry  Process. — See  page  387. 

Part  Chill  Roll.— See  page  403. 

Part  Ingot. — Butt  ingot:  see  page  47. 

Partial  Cementation. — See  page  67. 

Partial  Fracture. — See  page  1 79. 

Partially  Fusible  Cements. — See  page  69. 

Parting. — See  page  123. 

Parting  Plane. — See  page  123. 

Paiting  Sand. — See  page  298. 

Pass. — See  page  405. 

Pass  Over  Mill. — See  page  408. 

323 


324  PASSAGE— PEEL 

Passage  (obs.).— Tuyere. 

Passivated  Iron. — See  page  364. 

Passive  Break. — In.  connection  with  passivity:  see  page  364. 

Passive  Iron. — See  page  364. 

Passive  Resistance. — See  page  269. 

Passive  State. — See  page  364. 

Passivified  Iron;  Passivity. — See  page  364. 

Pasting. — See  page  300. 

Patch. — See  page  432. 

Patents. — In  coating  sheets:  see  page  432. 

Patent  Blacking. — See  page  298. 

Patent  Steel ;  Patented  Steel.— A  steel  heat  treated  so  as  to  contain 

a  large  proportion  of  sorbite;  the  same  as  sorbitic  steel. 
Patented  Wire. — See  page  509. 
Patience.— See  page  333. 
Pattern. — See  page  296. 
Pattern  Maker's  Rule. — See  page  296. 
Paweck  Process. — See  page  371. 
Paxson-Deemer  Converter. — See  page  24. 
Pea  Coal.— See  Coal. 
Pea  Coke. — See  page  97. 
Pean. — See  Pane. 
Pearlite. — See  page  273. 
Pearlite -Cementite. — See  page  273. 
Pearlite-Femte. — See  page  272. 
Pearlite  Point. — See  page  273. 
Pearlite  Range. — See  page  271. 
Pearlitic  Cementite. — See  page  273. 
Pearlitic  Ferrite. — See  page  272. 
Pearlitic  Range.— See  page  273. 
Pearlitic  Special  Steels.— See  page  445- 
Pearloid. — See  page  213. 
Pearly  Constituent. — See  page  273.     . 
Pearlyte.— See  page  273. 
Peat. — A  dark  brown  fuel  resulting  from  the    decay   of    small 

plants  and  mosses,  occurring  in  bogs  or  swamps.    It  contains 

up  to  80%  of  water,  and  must  accordingly  be  dried  before  using. 

It  is  practically  never  employed  in  metallurgy.    An  average 

sample,  after  drying,  shows: 

Carbon  56 .  o% 

Hydrogen 5.5 

Oxygen 29 . 5 

Nitrogen 1.5 

Ash 7-5 

Peat  Charcoal ;  Coke. — Produced  by  the  destructive  distillation  of 
peat;  it  is  not  of  metallurgical  importance. 

Peckham  Process. — See  page  387. 

Peel ;  Peel  Bar. — (i)  A  long  iron  bar,  flattened  out  at  one  end  like  a 
spade,  used  for  charging  or  withdrawing  material  from  a  furnace 
by  hand;  (2)  in  charging  machines,  the  arm  which  engages  with 


PEEL  CHARGING— PHASE  325 

the  charging  boxes  to  dump  their  contents  in  the  furnace;  (3) 
the  hoe-like  plate  on  the  end  of  a  rabble. 

Peel  Charging.— See  page  313. 

Peen ;  Pein.— See  Pane. 

Peening  Test— See  page  482. 

Peligot  Method.— See  Iron. 

Pellin  Hardness-testing  Machine. — See  page  478. 

Peltier  Effect.— See  page  209. 

Peltoid. — See  page  290. 

Pene.— See  Pane. 

Penetration. — Of  carbon:  see  page  67. 

Penetration  Twin. — See  page  124. 

Pentad;  Pentavalent. — See  page  86. 

Pepper  Blister.— See  Blister. 

Per-. — Chemical  prefix;  see  page  88. 

Percarbide. — See  page  278. 

Percussion  Test. — See  page  481. 

Percussive  Electric  Welding. — See  page  504. 

Perfect  Cleavage. — See  page  124. 

Perfect  Elasticity. — See  page  330. 

Perfect  Gas.— See  Gas. 

Period  of  Elasticity. — See  page  334. 

Periodic  Law. — See  page  85. 

Perlite.— See  page  273. 

Permanent  Distortion. — See  page  334. 

Permanent  Mold. — See  page  296. 

Permanent  Set. — See  pages  334  and  470. 

Permanent  Stretch. — See  page  336. 

Permissible  Working  Stress. — See  page  468. 

Peroxide  Theory. — Of  passivity:  see  page  364. 

Perpetual  (obs.). — Of  the  action  of  furnaces,  processes,  etc.,  con- 
tinuous. 

Perret  Method. — Of  quenching:  see  page  229. 

Perrins  Process.— See  page  490. 

Perturbation. — See  Curve. 

Peter  Process. — See  page  387. 

Petroleum. — A  heavy  yellowish  or  dark-colored  oil  of  natural 
origin.  It  has  a  high  calorific  power,  and  may  contain  a  little 
sulphur  which  is  usually  higher  in  the  Russian  than  in  ^the 
American  product.  It  is  used  to  a  certain  extent  for  heating, 
in  which  case  it  is  injected  into  the  furnace  in  the  form  of 
spray.  Its  composition  is  approximately: 

Carbon 85.0% 

Hydrogen 13.5 

Oxygen 1.5 

Petroleum  Furnace. — A  furnace  in  which  petroleum  is  used  for 
fuel.     It  is  usually  sprayed  in  (atomized)  with  a  jet  of  air  or  steam. 
Pettitt  Process.— See  page  22. 

Pewter. — Of  rails  which  are  soft  and  are  battered  in  service. 
Phantom. — See  page  289. 
Phase;  Phase  Doctrine;  Field.— See  Phase  Rule. 


326  PHASE  RULE 

Phase  Rule  (Gibbs). — Or  phase  doctrine  (Roozebopm);  a  rule 
for  finding  the  number  of  phases  that  can  exist  in  a  system 
containing  a  certain  number  of  components,  and  having  a  cer- 
tain number  of  degrees  of  freedom.  It  connects  together  the 
number  of  components,  degrees  of  freedom,,  and  possible 
phases  in  equilibrium  (Gibbs).  A  system  is  a  body  composed 
of  two  or  more  components  or  phases.  Bancroft  defines 
phase  as  "a  mass  chemically  and  physically  homogeneous  or 
a  mass  of  uniform  concentration,  the  number  of  phases  in  a 
system  being  the  number  of  different  homogeneous  masses,  or 
the  number  of  different  concentrations;"  and  components  as 
"the  substances  of  independently  variable  concentration  in 
the  phase  or  system  under  consideration."  Howe  says:  "The 
components  are  the  entities  in  play,  the  entities  of  which  we 
are  studying  the  reciprocal  behavior;  the  phases  are  the  states, 
physical  and  chemical,  in  which  these  components  exist  and 
into  which  they  pass."  A  careful  distinction  must  be  made 
between  the  terms  component  and  constituent:  the  constituents 
of  a  system  are  the  chemical  elements  or  compounds  present, 
or  capable  of  being  present,  as  such;  a  constituent  may  occur  in 
more  than  one  phase,  or  more  than  one  constituent  may  unite 
to  form  a  single  phase.  For  example,  the  constituent  water  may 
exist  at  the  same  time  both  as  ice  and  as  water;  the  constituents 
calcium  oxide  and  carbon  dioxide  (each  of  which  may  be  a  com- 
ponent) can  unite  to  form  the  single  component  calcium  carbo- 
nate. To  avoid  confusion  in  the  use  of  the  term  "phase"  which 
has  this  specific  meaning,  Turner  has  suggested  that  stage  be 
applied  to  indicate  different  conditions  or  structures  as  in  the 
case  of  pearlite. 

In  regard  to  the  applications  and  limitations  of  the  phase  rule, 
Howe  says  (Metallography^  231):  "It  is  a  most  remarkable  and 
valuable  generalization;  its  conceptions  help  greatly  toward 
getting  a  broad  outlook  on  metallography;  but  its  misconception 
has  brought  out  a  flood  of  obscuring  writings.  It  tells  us  about 
the  constitution  toward  which  alloys  tend,  that  which  they  reach 
when  equilibrium  is  complete,  when  all  tendencies  have  asserted 
themselves  and  have  been  compiled  with  completely.  But  it 
tells  us  nothing  directly  about  the  intermediate  stages  through 
which  those  alloys  pass  in  their  attempt  to  reach  that  equilibrium, 
nothing  about  alloys  which  are  out  of  equilibrium.  And  what- 
ever it  may  teach  us  indirectly  about  such  inequilibrium  (in- 
complete equilibrium)  is  so  hedged  about  with  the  direct  and 
indirect  results  of  that  inequilibrium  that  its  application  to  any 
individual  case  is  fraught  with  the  greatest  difficulty." 

Equilibrium  is  the  condition  of  a  system  with  regard  _  to  the 
existing  conditions.  If  the  system  is  normal,  i.e.,  that  which  can 
exist  under  the  given  conditions,  it  is  said  to  be  in  stable  equi- 
librium, otherwise  in  unstable  equilibrium.  If  a  system  is  in 
unstable  equilibrium,  any  change  in  the  conditions  tends  to 
cause  a  transformation  to  take  place,  i.e.,  a  change  to  stable 
equilibrium.  Where,  with  change  of  temperature  a  transforma- 
tion (thermal  transformation)  should  occur  at  a  definite  tempera- 


PHASE  RULE  327 

ture  (equilibrium  or  inversion  temperature)  but,  owing  to 
molecular  inertia  (lag,  hysteresis,  or  internal  friction),  cannot 
do  so  instantaneously,  a  certain  range  of  temperature  may  be 
traversed  before  the  tendency  is  great  enough  to  cause  the  trans- 
formation, after  which  the  slighest  disturbance  will  suffice. 
During  this  range  of  temperature  (metastable  range)  the  system 
is  said  to  be  in  metastable  or  indifferent  equilibrium ;  beyond  it 
(labile  range),  in  labile  equilibrium.  In  the  case  of  steel  in 
stable  equilibrium  above  or  below  the  transformation  range, 
reference  is  sometimes  made  respectively  to  the  hot  stable  state 
and  the  cold  stable  state.  Thermal  equilibrium  is  where  the 
members  of  a  system  are  at  the  same  temperature.  The  case 
of  the  cooling  of  solutions  which  can  be  cooled  without  solidifi- 
cation below  the  normal  freezing  point  is  called  surfusion  or 
undercooling.  Equilibrium  diagrams  are  those  which  show  the 
normal  relations  between  concentrations  (composition)  and 
temperatures  (and  in  some  cases  pressures);  where  metastable 
states  are  plotted  they  are  called  metastable  diagrams.  In  an 
equilibrium  diagram  the  different  regions  are  termed  phase 
fields.  Where  the  transformation  occurs  at  the  same  tempera- 
ture either  on  heating  or  cooling,  it  is  said  to  be  reversible ;  if, 
due  to  lag,  .at  different  temperatures,  an  irreversible  or  non- 
reversible  transformation  or  process.  If  the  transformation  can 
proceed  only  in  one  direction  without  any  reverse  change  at  all, 
it  is  then  termed  monotropic.  Where  the  radiation  from  a  body 
is  counterbalanced  by  an  equal  evolution  of  heat,  it  is  an  isother- 
mal transformation.  A  polymorphic  transformation  or  allo- 
tropic  transformation  is  where  the  change  is  from  one  form  to 
another,  as  from  gamma  into  alpha  iron. 

The  phase  rule  may  be  written  as  an  equation  of  equilibrium 
which  has  been  deduced  from  thermodynamical  considerations  as 

F  =  C  +  2  -  P 

F  =  degree  of  freedom;  C  =  number  of  components;  P  =  num- 
ber of  phases.  The  degree  of  freedom  (also  termed  degree  of 
liberty,  degree  of  constitutive  freedom,  and  degree  of  variability) 
is  whether  the  existing  constitution  of  a  system  has  such  a  degree 
of  stability  that  it  can  survive  a  change  of  temperature  or  of 
concentration,  or  cannot  (Howe;. 

An  invariant  or  non-variant  system  is  one  which  cannot 
survive  any  change  in  temperature,  pressure,  or  concentra- 
tion; a  mono  variant  system  is  one  which  can  survive  a  change 
in  any  one  of  these  conditions,  and  a  divariant  system  in  one 
which  can  survive  a  change  in  one  of  the  conditions  if  a  conform- 
able change  is  made  in  one  of  the  others.  "The  degree  of 
liberty  of  a  non-variant  system  is  o,  that  of  a  monovariant 
system  i,  and  of  a  divariant  system  2"  (Howe).  A  system  with 
n  components  can  exist  (a)  if  non-variant  in  n  +  2  phases,  (b) 
if  monovariant  in  n  +  i  phases,  and  (c)  if  divariant  in  n  phases. 
A  monovariant  system  is  called  a  case  of  complete  heterogene- 
ous equilibrium,  while  a  divariant  system  is  known  as  a  case 
of  incomplete  heterogeneous  equilibrium  (Bancroft).  "If  a 


328       PHENOCELLULAR  STRUCTURE— PHOSPHORUS 

system  is  uniform  throughout  its  whole  extent,  and  possesses  in 
every  part  identical  physical  properties  and  chemical  composi- 
tion, it  is  called  homogeneous.  Such  is,  for  example,  a  solution 
of  sodium  chloride  in  water.  An  equilibrium  occurring  in  such  a 
homogeneous  system  (such  as  the  equilibrium  occurring  in  the 
formation  of  an  ester  in  alcoholic  solution)  is  called  homogeneous 
equilibrium.  If,  however,  the  system  consists  of  parts  which 
have  different  physical  properties,  perhaps  also  different  chemical 
properties,  and  which  are  marked  off  and  separated  from  one 
another  by  bounding  surfaces,  the  system  is  said  to  be  hetero- 
geneous (non-homogeneous).  Such  a  system  is  formed  by  ice, 
water,  and  vapor,  in  which  the  three  portions,  each  in  itself 
homogeneous,  can  be  mechanically  separated  from  one  another. 
Where  equilibrium  exists  between  different,  physically  distinct 
parts  it  is  known  as  heterogeneous  equilibrium"  (Findlay, 
The  Phase  Rule,  5).  To  homogenize  is  sometimes  used  to  signify 
the  obtaining  of  equilibrium  for  given  conditions  of  temperature 
and  concentration. 

Le  Chatelier's  theorem  states  that  "any  change  in  the  fac- 
tors of  equilibrium  from  outside  is  followed  by  a  reverse  change 
within  the  system." 

Bancroft  suggested  that  "it  would  be  well  to  keep  the  term 
adsorption  for  effects  which  may  prove  to  be  due  primarily  to 
surface  tension,  and  to  treat  absorption  as  the  general  term 
applying  to  liquid  and  solid  solvents,  while  occlusion  would 
refer  only  to  the  formation  of  solid  solutions."  With  the  ob- 
ject of  explaining  this  adsorption  theory,  W.  R.  Whitney  says 
(Proc.  Am.  Electrochem.  Soc.,  1915,  187):  "I  cannot  accurately 
differentiate  between  absorption  and  adsorption.  We  usually 
have  adsorption  in  phenomena  going  on  at  a  surface  when  some- 
thing comes  to  it  and  clings  there.  But  a  sponge  is  made  of  a  lot 
of  interior  surfaces,  therefore  a  sponge  would  adsorb  and  not 
absorb.  I  think  you  will  find  the  water  is  held  on  the  surface 
in  the  pores.  Glass  surfaces  adsorb  from  solutions;  if  you 
analyze  the  surface  solution  you  will  find  the  material  in  the  solu- 
tion has  increased  in  concentration  on  the  surface  of  the  glass." 

Phenocellular  Structure. — See  page  126. 

Phenocryst. — Se  page  125. 

Philosopher's  Wool.— See  Zinc. 

Phosphate  Ore. — See  page  244. 

Phosphide  Phosphorus. — See  Phosphorus. 

Phospho-Ferrite. — See  page  272.  : 7 .-;  u  \ 

Phospho-Manganese. — See  page  353. 

Phosphoretic. — Phosphorous;  containing  phosphorus. 

Phosphoretic  (Phosphoric)  Cast  Iron ;  Pig. — See  page  346. 

Phosphorous  (adj.). — Containing  phosphorus. 

Phosphorus. — (i)  In  iron  ore:  see  page  243;  (2)  influence  on 
corrosion:  see  page  366. 

Phosphorus.— P;  at.  wt.,  31;  melt,  pt.,  43.3°  C.  (78°  F.);  boil, 
pt.,  269°  C.  (516°  F.);  sp.  gr.,  yellow,  1.82,  red,  2.25.  It  is 
never  found  in  the  free  state,  its  most  important  occurrence 
being  in  combination  with  oxygen  and  various  metallic  ele- 


PHOSPHORUS  ADDITIONS— PHYSICAL  PROPERTIES  329 

ments,  called  phosphates.  In  its  elemental  condition  it  may 
occur  in  one  of  two  allotropic  forms:  the  ordinary  variety  which 
is  a  colorless  or  yellow  wax-like  poisonous  solid,  and  another 
variety  of  reddish  color,  and  non-poisonous,  obtained  by  heat- 
ing the  ordinary  variety  to  between  240°  and  250°  G.  (464° 
and  482°  F.)  with  exclusion  of  air;  when  heated  to  above  260° 
C.  (500°  F.)  it  passes  back  to  the  yellow  variety.  This  latter 
is  very  inflammable  and  must  be  kept  under  water.  It  is  the 
most  undesirable  impurity  which  occurs  in  steel,  causing  cold- 
shortness  and,  perhaps,  to  a  slight  extent,  red-shortness.  It 
is  usually  limited  to  0.05%  in  basic,  and  0.10%  in  acid  steel, 
except  for  some  special  purpose.  In  cast  iron  it  makes  the 
molten  metal  more  fluid.  Baron  Juptner  suggests  that  in 
analogy  to  the  different  modifications  of  carbon  it  is  possible 
to  describe  one  form  of  phosphorus  which,  upon  treatment  of 
steel  with  dilute  acids,  escapes  as  PH3,  and  which  causes  cold- 
shortness,  as  hardening  phosphorus,  while  the  modification, 
insoluble  in  dilute  acids,  may  be  named  phosphide  phosphorus. 

Phosphorus  Additions. — See  Recarburization. 

Phosphorus  Banding. — See  page  289. 

Phosphorus  Reagent. — For  detecting  phosphorus  on  etching:  see 
page  287. 

Photogram;  Photograph. — See  page  284. 

Photometer. — See  page  208. 

Photomicrograph;  micrography;  microscopy. — Seepage  284. 

Physic ;  Physick ;  Physicking. — A  term,  usually  restricted  to  the 
puddling  and  the  crucible  process,  for  an  addition  made  with  the 
object  of  assisting  in  the  removal  of  the  impurities,  and  the  more 
rapid  working  of  the  heat;  it  may  act  chemically  or  simply  as  a 
flux.  It  may  consist  of  a  mixture  of  manganese  dioxide  with  salt 
or  a  little  ground  charcoal,  sal  ammoniac,  prussiate  of  potash, 
ground  glass,  fluorspar,  etc. 

Physical  Analysis. — See  page  284. 

Physical  Formulae. — See  page  337. 

Physical  Hardness.— See  page  331. 

Physical  Metallurgy. — Suggested  by  Rosenhain  for  "that  great 
branch  of  the  knowledge  of  metals  which  has  to  a  large  extent 
grown  up  during  the  last  fifty  years — a  branch  which  concerns 
itself  with  the  nature,  properties  and  behavior  of  metals  and  of 
alloys  as  such,  as  distinct  from  the  far  older  branch  of  metallurgy 
which  deals  with  the  reduction  of  metals  from  their  ores.  Hith- 
erto the  term  Metallurgy  has  indeed  been  almost  entirely  confined 
to  this  latter  meaning,  and  those  who  have  grown  old  in  this  idea 
are  a  little  apt  to  resent  an  innovation  which  gives  to  the  old  term 
Metallurgy  a  wider  and  more  general  meaning  than  it  formerly 
bore  so  as  to  include  the  newer  knowledge  of  metals.  This  inevit- 
able widening  ot  the  old  term,  however,  demands  a  subdivision, 
so  that  the  department  of  metallurgy  which  relates  to  the  reduc- 
tion of  metals  and  their  refining  may  well  be  termed  Process  or 
Chemical  Metallurgy,  leaving  to  tne  younger  branch  of  the 
science  the  newer  term  Physical  Metallurgy."  (Phys.  Met,,  i.) 

Physical  Properties.— (See  also  Testing.)    Those  properties  ex- 


330  PHYSICAL  PROPERTIES 

hibited  by  a  body  which  do  not  involve  any  change  in  its  chemical 
composition.  The  general  treatment  of  the  subject  in  treatises 
and  text  books  is  usually  under  the  title  of  Strength  of  Materials 
or  Properties  of  Materials  for  which  Ewing  gives  the  following 
definition  (Ency.  Brit.):  "That  part  of  the  theory  of  engineering 
which  deals  with  the  nature  and  effects  of  stresses  in  the  parts  of 
engineering  structures.  Its  principal  object  is  to  determine  the 
proper  size  and  form  of  pieces  which  have  to  bear  given  loads,  or, 
conversely,  to  determine  the  loads  which  can  be  safely  applied  to 
pieces  whose  dimensions  and  arrangement  are  already  given. 
It  also  treats  of  the  relation  between  the  applied  loads  and  the 
changes  of  form  which  they  cause.  The  subject  comprises 
experimental  investigation  of  the  properties  of  materials  as  to 
strength  and  elasticity,  and  a  mathematical  discussion  of  the 
stresses  in  ties,  struts,  beams,  shafts  and  other  elements  of  struc- 
tures and  machines."  When  a  body  possesses  the  same  proper- 
ties, no  matter  in  what  direction  it  is  tested,  it  is  said  to  be 
isotropic;  when  they  differ  in  different  directions,  anisotropic, 
aeolotropic  or  eplotropic.  Those  here  discussed  are  principally 
what  are  met  with  in  testing  (q.v.)  materials. 

The  strength  or  tenacity  of  a  body  is  its  resistance  to  rupture 
or  breaking,  and  may  be  of  the  following  kinds: 

1.  Tensile    (tensional)    strength    (sometimes   referred   to   as 
•  tensile  strain) :  resistance  to  being  pulled  apart. 

2.  Compressive  strength:  resistance  to  being  crushed. 

3.  Shearing    strength:  resistance  to   being  sheared  or  cut; 
the  next  two  are  also  of  this  kind. 

4.  Torsional  strength:  resistance  to  torsion  or  being  twisted. 

5.  Bending,    transverse    or    flexural  strength:  resistance  to 
flexure  or  bending. 

A  division  may  also  be  made  into 

6.  Static  strength:  resistance  to  loads  slowly  and  gradually 
applied. 

7.  Dynamic  strength:  resistance  to  loads  suddenly  applied 
(shocks)  or  repeated  stresses. 

Elasticity  is  the  ability  of  a  body  to  regain  its  original  shape 
after^  having  been  distorted.  This  definition  covers  perfect 
elasticity ;  however  as  bodies  seldom  meet  this  condition  entirely 
they  are  said  in  such  case  to  possess  imperfect  elasticity.  The 
distortion  from  which  an  elastic  body  can  recover  may  be  termed 
elastic  deformation  or  elastic  strain  and  the  maximum  stress 
under  which  this  condition  obtains  is  called  the  elastic  limit, 
corresponding  to  the  elastic  strength  or  elastic  limit  strength  for 
the  material.  In  the  Quarterly  Mathematical  Journal  of  April, 
1855,  Sir  William  Thompson  (Lord  Kelvin)  discussed  at  some 
length  the  thermo -elastic  properties  of  material,  and  showed 
mathematically  that  elastic  matter  when  stressed  absorbs  heat, 
that  is,  its  temperature  as  indicated  by  a  thermometer  is  lowered; 
but  when  the  stressing  is  carried  beyond  the  elastic  limit  and  the 
strain  becomes  permanent,  the  body  gives  out  heat,  that  is,  its 
temperature  as  indicated  by  a  thermometer,  rises  (Capp). 
Rigidity  or  stiffness  is  the  property  by  virtue  of  which  bodies 
resist  change  of  snape. 


PHYSICAL  PROPERTIES  331 

Resilience,  or  the  work  of  resistance  of  materials,  is  frequently 
used  in  the  same  sense  as  elasticity.  It  connotes  springiness  and 
should  properly  be  restricted  to  the  amount  of  work  absorbed 
when  a  body  is  stressed  within  its  elastic  limit  and  which  can  be 
recovered  when  the  stress  is  removed;  this  is  sometimes  also 
termed  elastic  resilience  which  however  seems  redundant.  De- 
pending upon  the  nature  of  the  stress  there  may  be  tensile  or 
compressive  resilience,  shearing,  bending  or  flexural  resilience, 
and  torsional  resilience.  The  modulus  of  resilience  is  the  work 

Eer  unit  volume  in  stressing  up  to  the  elastic  limit  and  is  equiva- 
mt  to  half  the  product  of  the  elastic  limit  strength  and  the  cor- 
responding unit  deformation. 

The  opposite  of  elasticity  or  resilience,  when  the  slightest 
distortion  or  deformation  (change  of  form)  is  permanent  is 
called  plasticity:  no  substance  possesses  either  property  ab- 
solutely. Plastic  or  viscous  materials  flow  under  a  compressive 
load. 

Hardness  is  resistance  to  indentation,  or  abrasion  or  attrition 
(wear  from  rubbing  or  crushing).  Abrasive  hardness  is  also 
known  as  scratch  hardness.  Static  hardness  is  where  the  force 
acts  relatively  slowly  as  in  the  Brinell  ball  test  (see  Testing,  page 
477)  or  ordinary  abrasion.  Dynamic  hardness  is  where  the 
force  acts  suddenly  as  in  the  scleroscope  test  (see  Testing,  page 
478);  this  term  has  also  been  suggested  by  Turner  to  cover 
resistance  to  the  action  of  running  water,  to  a  sand  blast,  etc. 
A  substance  may  be  said  to  possess  chemical  hardness  when 
this  is  due  principally  to  its  composition;  physical  hardness 
when  due  to  its  chemical  and  mechanical  structure;  and  mechan- 
ical hardness  when  resulting  from  being  worked,  particularly 
cold,  also  known  as  work  hardness  and  strain  hardness. 

Brittleness  is  the  tendency  to  rupture  under  shock  or  loads 
suddenly  applied;  the  opposite  of  this  is  toughness.  Hardness 
and  brittleness  are  not  necessarily  allied,  as  shown  by  manganese 
steel  which  is  very  hard  and  yet  at  the  same  time  may  be  tougher 
than  ordinary  steel. 

Malleability  is  the  property  which  permits  a  metal  to  be  ham- 
mered or  pressed  out  into  shape  without  cracking:  ductility 
is  practically  a  synonymous  term  but  is  applied  more  especially 
to  that  form  of  toughness  which  permits  a  metal  to  be  drawn  or 
drawn  down.  It  was  noted  by  A.  LeChatelier  that  between  80 
and  120°  C.  (175  and  250°  F.)  there  was  a  critical  mechanical 
temperature  at  which  steel  exhibited  its  minimum  ductility. 
Ordinarily  it  is  understood  that  any  reference  to  the  ductility 
of  a  body  means  when  it  is  cold,  otherwise  the  terms  hot  ductility 
and  cold  ductility  (only  in  contradistinction)  would  be  used. 
The  term  cito-ductile  is  sometimes  applied  to  a  body  which  can 
be  stretched  suddenly  without  rupture. 

A  force  acting  on  a  body  is  known  as  a  stress :  if  it  affects  the 
entire  body  (e.g.,  gravity)  it  is  termed  a  body  force  or  volume 
force ;  if  it  acts  only  upon  local  portions  (the  pressure  of  one 
object  against  another)  it  is  a  surface  force  or  surface  traction. 
A  force  or  stress  may  act  either  from  outside  a  body  (external 


332  PHYSICAL  PROPERTIES 

force)  or  from  within  (internal  force).  "The  terms  axial  forces 
and  axial  stresses  are  used  to  include  both  tension  and  compres- 
sion acting  upon  a  bar,  it  being  understood  that  the  resultant 
of  the  applied  forces  acts  along  the  axis  of  the  bar.  The  axial 
force  P  is  often  called  a  load.  It  is  always  understood,  unless 
otherwise  stated,  that  the  stresses  due  to  an  axial  load  or 
concentric  load  are  uniformly  distributed  over  the  section  area, 
and  this  is  called  the  case  of  simple  axial  stress"  (Merriman). 
Stresses  (or  strains)  may  be  (a)  normal  or  direct  (tensile  or 
compressive),  (b)  shearing,  flexural  or  tangential,  and  (c)  a 
component  of  the  two  or  oblique.  If  the  stress  is  in  only  one 
direction  it  is  a  simple  stress  ;  if  in  different  directions  a  compound 
stress.  "It  may  be  shown  that  any  state  of  stress  which  can 
possibly  exist  at  any  point  of  a  body  may  be  produced  by  the 
joint  action  of  three  simple  pull  or  push  stresses  in  three  suitably 
chosen  directions  at  right  angles  to.  each  other.  These  three 
axes  are  called  principal  stresses,  and  their  directions  are  called 
axes  of  principal  stress.  These  axes  have  the  important  prop- 
erty that  the  intensity  of  stress  along  one  of  them  is  greater,  and 
along  another  it  is  less,  than  in  any  other  direction.  These  are 
called, .  respectively,  the  axes  of  greatest  and  least  principal 
stress"  (Ewing).  As  in  the  case  of  a  liquid  at  rest,  but  where 
there  are  balanced  stresses  exerted  upon  it,  such  an  effect  is 
termed  a  fluid  stress.  Those  directly  produced  by  loadings  may 
be  called  primary  stresses ;  and  further  stresses,  acting  in  con- 
junction with  these,  secondary  stresses  (Carpenter). 

The  term  pure  stress  is  employed  where  only  one  kind  of 
stress  exists.  Where  a  plane  is  acted  upon  only  by  forces  normal 
to  it,  this  is  sometimes  called  pure  normal  stress.  Where  a  plane 
is  acted  upon  only  by  forces  parallel  to  it  it  is  sometimes  called 
pure  shearing  stress.  Another  use  of  the  term  pure  stress  is 
with  respect  to  any  and  all  planes  that  can  be  imagined  drawn 
in  the  interior  of  a  body.  Where  the  forces  acting  upon  the  body 
have  such  values  that  there  can  be  no  shearing  stresses  within  it, 
the  case  is  called  one  of  pure  internal  normal  stress.  The  term 
pure  flexure  is  used  for  a  part  of  a  beam  where  there  are  no  ver- 
tical shears  (Merriman).  True  stresses  are  those  actually 
determined  while  those  simply  calculated  are  apparent  stresses. 
Owing  to  various  conditions,  such  as  irregular  cooling,  cold 
distortion,  etc.,  an  unstressed  body  is  only  theoretically  possible, 
and  consequently  all  bodies  are  more  or  less  (internally)  self- 
stressed  or  self-strained.  A  body  with  internal  strains  at  a 
minimum  is  said  by  Pearson  to  be  in  a  state  of  ease.  Heyn  calls 
outside  stresses  acting  on  such  a  body  additional  stresses. 
Internal  strains  may  be  set  up  by  unequal  expansion  or  con- 
traction in  different  parts  of  a  piece  due  to  irregular  heating  or  cool- 
ing or  to  transformations  (transformation  strain)  of  state  (see 
Metallography,  p.  264).  In  material  cold  drawn  in  the  direction 
of  its  axis  the  outer  layers  are  under  tension  and  the  inner  layers 
are  under  compression,  whereas  in  the  case  of  cold-rolled  and 
cold-hammered  bars  the  reverse  is  true.  In  either  case  if  the 
tensile  stresses  are  excessive  rupture  may  be  caused  (spontaneous 


PHYSICAL  PROPERTIES  333 

cracking — in  the  case  of  the  cold-rolled  or  cold-hammered  bars, 
internal  rupture,  fracture,  or  defect).  If  such  strains  are  not 
excessive  they  may  be  removed  by  a  suitable  annealing  (see 
Heat  Treatment,  p.  231).  When  a  body  is  struck,  vibrations  or 
waves  are  set  up  in  it,  the  effect  depending  on  the  frequency  or 
number  per  second.  In  conducting  experiments  the  stress 
originally  present  is  known  as  the  initial  stress.  The  range  of 
stress  is  the  algebraic  difference  between  the  maximum  and  the 
minimum;  the  mean  stress  is  half  the  algebraic  sum. 

The  effect  of  a  stress  depends  largely  upon  the  manner  in 
which  it  is  applied.  Thus  when  suddenly  applied,  as  a  blow 
(sudden  load,  accelerated  stress,  impact  or  shock),  it  has  a  con- 
siderably greater  effect  than  a  stress  slowly  and  steadily  applied 
(static  stress  or  load).'  Again,  if  the  stress  is  repeated,  i.e., 
applied  a  great  number  of  times,  each  application  being  made 
before  the  material  has  been  given  time  to  recover  from  the 
preceding,  it  will  eventually  break,  even  though  the  stress  is 
below  the  elastic  limit  as  ordinarily  understood.  For  practical 
purposes,  if  the  stress  is  sufficiently  small,  and  below  what  may  be 
termed  the  fatigue  limit  or  endurance  limit,  its  repetition  may  be 
indefinitely  continued.  Alternate  stresses  are  similar  in  effect, 
but  are  where  the  force  acts  first  in  one  direction  and  then  in  the 
opposite.  It  will  therefore  be  seen  that  stresses  may  vary  from 
+  to  —  (e.g.,  tensile  to  compressive)  or  from  a  higher  to  a  lower 
value  with  the  same  sign  (stress  difference  or  limiting  stresses). 
They  are  termed  dynamic  stresses  or  loads  (producing  corre- 
sponding dynamic  deformations  or  strains)  and  are  covered  by 
Wohler's  law,  which  may  be  stated  thus:  Rupture  of  material 
may  be  caused  by  repeated  vibrations,  none  of  which  attains  the 
actual  breaking  limit;  the  difference  of  the  limiting  strains  are 
sufficient  for  the  rupture  of  the  material.  When  a  metal  is 
subjected  to  a  stress  its  component  particles  may  become  so 
disturbed  and  disarranged  (see  Plastic  Deformation,  under 
Metallography,  p.  279),  within  the  limits  of  elasticity  be  it 
understood,  that  after  the  removal  of  the  stress,  and  it  is  left 
at  rest,  some  time,  and  in  certain  cases  considerable  time,  must 
elapse  before  the  particles  will  have  spontaneously  readjusted 
themselves  as  they  originally  were.  The  term  fatigue  or  elastic 
break-down,  is  meant  to  indicate  such  disturbance;  the  terms 
refreshment,  recovery,  aging,  or  elastic  after-working,  restora- 
tion of  the  metal  to  its  original  state;  and  the  term  patience,  the 
time  required  for  that  restoration.  If  a  body  is  subjected  to  a 
change  of  temperature  and  is  acted  upon  by  a  force  which  tends  to 
prevent  the  corresponding  expansion  or  contraction,  stresses  are 
set  up  which  may  be  termed  temperature  stresses. 

Intensity  of  stress  (unit  stress)  is  the  force  exerted  per  unit  of 
area;  in  English  units,  pounds  or  gross  tons  (England)  per  square 
inch,  and  in  metric  units,  kilograms  per  square  millimeter  or 
per  square  centimeter. 

Every  stress,  no  matter  how  small,  produces  a  corresponding 
strain  (tensile  strain,  compressive  strain,  etc.)  or  deformation  in 
the  shape  of  the  body  acted  upon,  and  which  increases  with  the 


334  PHYSICAL  PROPERTIES 

stress.  The  stress  and  the  corresponding  strain  are  directly 
proportional  up  to  a  certain  point,  called  the  elastic  limit  (limit 
of  linear  elasticity,  etc.),  below  which,  by  removing  the  stress, 
the  corresponding  strain  disappears  and  the  body  returns  to  its 
original  shape,  or,  in  other  words,  is  elastic.  This  fact  constitutes 
Hooke's  law  or  the  limit  of  proportionality.  After  this  period 
has  passed,  the  strain  increases  more  rapidly  than  the  stress 
causing  it,  and  if  the  stress  be  now  removed,  the  body  will 
partially,  but  not  entirely,  regain  its  original  dimensions,  as  it 
has  received  a  permanent  distortion  (permanent  set,  overstrain, 
plastic  strain).  Gerstner's  law  is  that  elastic  deformations  are 
proportional  to  the  loads  producing  them  both  before  and  after 
permanent  set.  Relative  deformation  is  the  deformation  per 
linear  unit.  The  period  before  the  elastic  limit  is  reached  is 
known  as  the  period  of  elasticity.  The  point  at  which  the  elastic 
limit  is  exceeded  is  called  the  yield  point  or  breaking-down  point. 
If  a  material  has  been  overstrained  (a  .permanent  set  produced) 
and  is  immediately  reloaded  it  will  be  found  to  have  no  true 
elastic  limit  (although  its  yield  point  will  be  about  the  same),  also 
its  ductility  is  lowered.  If  it  is  allowed  to  recover  by  resting 
(aging)  several  days  or  weeks,  or  is  heated  for  a  few  minutes  at 
the  temperature  of  boiling  water,  a  true  elastic  limit  will  be  found, 
but  higher  than  in  the  original  material,  and  also  the  ductility 
will  be  increased  (spontaneous  annealing).  If,  instead  of  again 
testing  in  tension,  it  is  tested  in  compression,  the  elastic  limit  will 
be  lower  than  in  the  original  material,  but  not  necessarily  to  the 
extent  that  the  tensile  elastic  limit  and  yield  point  have  been 
raised.  This  is  kno  wn  as  the  effect  of  hardening,  or  the  hardening 
effect  of  permanent  set.  Vical's  experiment  proved  that  heavily 
loaded  material  is  likely  to  yield  ultimately  under  loads  that  are 
sustained  for  short  periods  without  apparent  injury.  Emory's 
process  for  increasing  the  elastic  limit  of  material  (particularly 
structural  material  such  as  eye  bars)  consisted  in  cold  straining 
the  material  tensily  slightly  above  its  elastic  limit  or  yield  point; 
the  load  was  then  removed  and  the  material  annealed  at  a  very 
low  temperature,  say  not  over  300  or  400°  C.  (570  or  750°  F.). 
The  effect  of  the  cold  straining  was  to  destroy  the  true  elasticity 
limit  of  the  material  which  was  restored  to  a  higher  point  than 
before,  by  the  annealing.  The  modulus  (rarely  module)  or 
coefficient  of  elasticity  or  Young's  modulus  (first  applied  for 
extension  only)  is  the  ratio,  within  the  limits  of  elasticity,  of  the 
stress  to  the  corresponding  strain,  e.g.,  the  load  in  pounds  per 
square  inch  divided  by  the  deformation  in  fractions  of  an  inch  for 
each  inch  of  gaged  length  of  the  specimen.  It  may  be  said  to  be 
the  stress  which  would  have  to  be  applied  to  stretch  the  piece  to 
double  its  original  length  assuming  it  to  be  perfectly  elastic. 
This,  of  course,  is  impossible  as  the  limit  of  elasticity  of  prac- 
tically any  material  is  passed  when  it  has  been  deformed  to  about 
o.ooi  of  its  length.  For  steel  in  tension  or  compression  it 
varies  from  about  26,000,000  to  31,000,000  pounds  per  square 
inch,  the  more  usual  limits  being  between  28,000,000  and 
30,000,000  pounds  per  square  inch.  The  corresponding  values 


PHYSICAL  PROPERTIES 


335 


in  the  metric  system  (kilograms  per  square  millimeter),  wide 
limits,  1828  to  2179;  usual  limits,  1969  to  2109.  The  values  for  a 
material  in  tension  (modulus  of  longitudinal  extension  or  ex- 
tensibility) are  generally  slightly  higher  than  those  for  compres- 
sion (modulus  of  compression  or  compressibility  or  bulk  modu- 
lus). The  modulus  of  elasticity  "may  also  be  called  modulus  of 
stiffness  since  it  is  a  direct  measure  of  the  rigidity  of  a  body 
(modulus  of  rigidity)  or  an  inverse  measure  of  its  flexibility;  a 
modulus  of  flexibility  would  be  the  reciprocal  of  the  modulus  of 
elasticity,  but  Prof.  A.  B.  W.  Kennedy  has  taken  for  such  a 
modulus  of  specific  extension  the  stretch  in  thousandths  of  an 
^  inch  on  a  length  of  10  inches  under  a  stress  of  1000  pounds  per 
*  square  inch.  Its  reciprocal  multiplied  by  10,000,000  is  the 
modulus  of  elasticity"  (Johnson).  The  shearing  modulus  of 
elasticity  (modulus  of  elasticity  for  shear;  modulus  of  shear)  is 
the  ratio  of  the  shearing  stress  to  the  corresponding  an  gular  strain, 


Steel 


White  Cast  Iron 


1OO 

—  —  ^ 

,  /• 

-^ 

~^£*rc 

u 

160000 
12OOOO 

V; 

f 

"<: 

HJ..'°!j/ 

S,^  _^~ 

^Jfe 
.--^X 

-~—  ' 

:^ 

-  — 

8OOOO 

9>4 

^ 

£ 

ktdnes*-, 
,    Mtf 

<*<&£• 

l\ 
«g£> 

^ 

"""""  «. 

•^ 

4QOOO 

o 

f 

\      p 

.*< 

r 

^ 

.—  _Iena 

City 

F 

0 

1.0  1.5          2.0         2.5         3.0         3.5         4.O          4,5 

Percentage  of  Carbon 

LEGEND;  Tenacity  

Hardness 

Ductility  I 

Percent  Ferrite  or  Cementite  __.__._ 

FIG.  48. — Physical  properties  and  assumed  microscopic  constitu- 
tion of  the  pearlite  series,  graphiteless  steel  slowly  cooled,  and 
white  cast  iron.  (Howe,  "Iron,  Steel  and  Other  Alloys.") 

and  is  two-fifths  of  the  modulus  for  extension.  "  The  volumetric 
modulus  of  elasticity  of  a  solid  body  for  an  equal  stress  in  all 
directions  is  two-thirds  of  Young's  modulus  which  applies  only  to 
direct  stress  in  one  plane  and  its  accompanying  deformation" 
(Johnson).  For  compression  it  is  termed  the  modulus  of  cubic 
compressibility. 

If  the  stress  be  increased  sufficiently,  the  body  will  eventually 
be  broken  or  else  distorted  to  such  an  extent  that  the  force  can  no 
longer  act,  and  in  the  former  case  this  maximum  stress  (maximum 
load)  applied  is  known  as  the  ultimate  strength  of  the  body 
(sometimes  referred  to  as  the  ultimate  stress).  The  elastic 
ratio  is  the  ratio  between  the  elastic  limit  and  the  ultimate 
strength,  the  former  figure  being  divided  by  the  latter  ;|it  is 
sometimes  expressed  as  a  percentage. 


336  PHYSICAL  PROPERTIES 

The  maximum  tensile  stress  (tensile  strength)  does  not  neces- 
sarily correspond  with  the  breaking  load  (breaking  or  tearing 
stress)  at  the  moment  of  rupture,  although  this  distinction  is  not 
always  made,  on  account  of  the  reduced  cross-section.  Here 
as  the  material  is  stretched  longitudinally,  it  is  obvious  that  it 
must  contract  with  respect  to  its  cross-section.  This  contrac- 
tion, however,  even  in  the  case  of  a  body  having  originally  the 
same  cross-section  throughout,  is  not  uniform,  But  at  some  por- 
tion an  action  called  necking  or  bottling  occurs,  i.e.,  the  contrac- 
tion is  much  more  pronounced  and  rupture  will  occur  there. 
The  amount  of  permanent  stretch  upon  rupture  is  called  the 
elongation  (extension  or  stretch)  and  is  usually  expressed  as  a 
percentage  of  the  original  length,  e.g.,  25%  in  8  inches.  This 
percentage  is  a  function  of  the  relation  of  length  to  cross-section 
(see  Testing,  page  473)  and  therefore,  in  reporting  it,  the  di- 
mensions of  the  specimen  in  question  should  always  be  given. 
(Tensile  or  compressive  deformations  are  stated  in  terms  of  the 
original  length  or  thickness;  shearing  or  torsional  deformations 
in  radian  (TT)  measure.  The  difference  between  the  original 
cross-sectional  area  and  that  at  the  point  of  rupture  (the  small- 
est) is  called  the  reduction  of  area  (contraction  of  area,  or  rarely, 
contraction  of  section,  or  striction),  and  is  generally  stated  as  a 
percentage  of  the  original.  Specific  tenacity  is  the  tensile 
"strength  of  a  material  expressed  as  the  length  of  a  bar  which, 
if  suspended  vertically,  is  just  sufficient  to  break  under  its  own 
weight"  (Rosenhain).  "It  is  a  fact  of  observation  that  when  a 
metal  body  is  elongated  by  an  external  force  from  /  to  /  +  \l 
(inside  the  elastic  limit),  it  contracts  laterally  about  one-fourth 
of  its  proportionate  elongation.  Hence,  if  the  original  diameter 

were  d,  its  diameter  after  stretching  would  be  d d.     This 

4 

ratio  of  lateral  to  longitudinal  deformation,  under  longitudinal 
external  forces,  is  called  Ppisson's  ratio"  (Johnson). 

In  the  case  of  compression  "there  is  no  such  thing  as  an  ulti- 
mate strength  of  a  plastic  body.  There  is,  however,  a  definite 
apparent  elastic  limit,  the  same  as  in  tension.  Beyond  this  the 
material  simply  spreads"  (Johnson).  This  is,  therefore,  the 
elastic  compressive  strength  or  compressive  strength.  "The 
term  bearing  compression  is  in  common  use  for  the  sidewise 
compression  brought  upon  a  rivet  by  the  tension  in  the  plate. 
Rivets  are  more  apt  to  fail  by  shearing  than  by  bearing  com- 
pression" (Merriman).  The  ductility  is  indicated  by  the 
shortening  or  ultimate  shortening  (upon  rupture)  which  however 
is  rarely  determined,  for  obvious  reasons,  particularly  in  the  case 
of  very  duclile  bodies. 

"When  a  beam  is  laid  upon  supports  its  weight  and  the 
weight  of  its  load  are  borne  by  the  supports  which  exert  reactions 
upward  against  the  beam.  The  vertical  shear  for  any  section  of 
a  beam  is  a  measure  of  the  tendency  to  shearing  along  that 
section  .  .  .  being  greatest  near  the  supports  .  .  .  The  usual 
method  of  failure  of  beams  is  by  cross-breaking  or  transverse 
rupture.  This  is  caused  by  the  external  forces  producingjrota- 


PHYSICAL  PROPERTIES  337 

tion  around  some  point  in  the  section  of  failure  (plane  of  shear). 
Resisting  shear  is  the  name  given  to  the  algebraic  sum  of  the 
internal  vertical  stresses  in  any  section,  and  vertical  shear  is  the 
name  for  the  algebraic  sum  of  the  external  vertical  forces  on  the  left 
of  the  section.  Resisting  moment  is  the  name  given  to  the  alge- 
braic sum  of  the  moments  of  the  internal  horizontal  stresses  with 
reference  to  a  point  in  the  section,  and  bending  moment  is  the 
name  for  the  algebraic  sum  of  the  moments  of  the  external  forces 
on  either  side  of  the  section  with  reference  to  the  same  point" 
(Merriman,  Mechanics  of  Materials,  93-98).  Simple  shear  is 
where  there  are  only  two  principal  opposite  forces  of  equal  value. 
Single  shear  (in  the  case  of  rivets,  for  example)  is  where  the 
object  is  supported  at  only  one  end;  in  the  case  of  double  shear 
both  ends  are  supported.  Flexural  rigidity  is  used  in  the  same 
sense  as  flexural  or  shearing  strength,  the  resistance  offered  to 
flexural  stress.  Transverse  strain  or  deformation  is  also  termed 
detrusion.  If  a  beam  or  bar  is  supported  at  the  ends  against  a 
force,  within  the  elastic  limit,  acting  at  some  point  between, 
bending  will  result  whereby  the  concave  surface  is  in  compres- 
sion and  the  convex  surface  is  in  tension.  It  is  assumed  that 
the  material  is  composed  of  infinitely  thin  leaves  or  fibers  and 
the  term  fiber  stress  or  maximum  fiber  stress  is  used  to  indicate 
the  force  acting  at  the  surfaces  which  are  necessarily  affected  to 
the  greatest  extent  since  they  undergo  the  greatest  amount  of 
deformation.  Since  the  force  changes  from  plus  to  minus  there 
must  be  some  plane  where  it  is  zero,  and  this  is  called  the  neutral 
surface ;  the  neutral  axis  is  the  line  of  intersection  of  the  neutral 
surface  with  any  plane  normal  to  it. 

Physical  Formulae. — From  time  to  time  empirical  formulae 
have  been  proposed  to  calculate  the  physical  (tensile)  properties 
or  as  a  basis  for  a  direct  comparison  of  the  properties  of  two 
samples  either  of  the  same  composition  but  differently  treated,  or 
of  different  composition  and  similar  or  dissimilar  treatment. 
Of  the  first  class  (tensile  properties  or  structural  properties)  it 
may  be  said  they  are  based  on  the  assumption  that  the  properties 
are  additive,  i.e.,  proportional  to  the  composition  or  a  summation 
of  the  properties  of  the  individual  components.  This,  un- 
fortunately for  the  purpose,  is  usually  far  from  being  the  case, 
and  in  addition  there  are  so  many  other  factors  entering  into  the 
problem,  such  as  size,  mechanical  and  thermal  treatment,  that  to 
determine  accurately  their  bearing  would  generally  be  much 
more  difficult,  and  even  the  real  result  would  be  left  in  consider- 
able doubt,  than  to  make  a  direct  test. 

Tensile  Formulae. — These  in  turn  may  be  divided  into:  (a) 
chemical  formulae,  based  on  ultimate  chemical  composition; 
(b)  structural  formulae,  based  on  microscopic  or  proximate 
chemical  analysis.  Sauveur  distinguishes  between  proximate 
structural  composition,  e.g.,  ferrite  and  pearlite,  or  cementite  and 
pearlite,  and  ultimate  structural  composition,  e.g.,  the  total 
ferrite  and  cementite  both  free  and  contained  in  pearlite. 

(i)  Chemical  Formulae. — Bauschinger's  formula  for  tensile 
strength  of  Bessemer  steel : 
22 


338  PHYSICAL  PROPERTIES 

T.  S.  =  43-64  d  +  C2) 

T.  S.  in  kilograms  per  square  millimeter;  C  =  carbon  %. 
H.  H.  Campbell's  formulae  for  tensile  strength: 

(a)  for  acid  steel,  carbon  by  combustion: 

\        T.  S.  =  40,000  +  1000  C  +  1000  P  +  x  Mn  +  R 

(b)  for  basic  steel,  carbon  by  combustion: 

T.  S.  =  41,500  +  770  C  +  1000  P  +  y  Mn  +  R 

The  strength  is  in  pounds  per  square  inc'h.  C,  P,  and  Mn  are  the 
values  of  these  elements  given  in  hundredths  of  a  percent.  The 
coefficients  x  and  y  are  given  in  tables  (see  Manufacture  and 
Properties  of  Iron  and  Steel,  391).  R  is  a  variable  to  allow  for 
heat  treatment  which  must  be  specially  determined.  See 
modified  formulae  below  as  proposed  by  Merriman. 

Cunningham's  formula  for  tensile  strength  for  acid  and  basic 
open  hearth  steels,  based  on  his  values  for  pure  iron,  carbon,  and 
phosphorus,  may  be  stated  as  follows : 

T.  S.  =  40,000  +  100,000  C  +  100,000  P 

T.S.  in  pounds  per  square  inch;  values  for  C  and  P  in  percent. 
Deshayes'  formulae : 

(a)  Tensile  strength: 

T.  S.  =  30.09  +  18.05  C  +  36.11  C2 

T.  S.  in  kilograms  per  square  millimeter;  C  =  percentage  of 
carbon. 

(6)  Elongation: 

E2o  =  42  -  56  C 

EIO  =  35  —  30  C 

E2o  and  EIO  are  percentage  of  elongation  in  lengths  of  20  and  10 
centimeters  (approximately  8"  and  4")  respectively;  C  =  per- 
centage of  carbon. 
Howe's  formulae  for  elongation,  percent  in  ^  inches : 

(a)  for  steel  under  0.50%  carbon: 

E  =  33  -6o(C2+o.i) 

(b)  for  steel  between  0.50  and  1.00%  carbon: 


E  =  12  —  11.9  ^/C  -  0.5 

Merriman's  formulae  for  tensile  strength : 
(a)  Deduced  from  Campbell's  formulas: 

Acid  steel:   T.  S.  =  40,000  +  68,000  C  +  100,000  P  +  80,000 
CM; 

Basic  steel:  T.  S.  =  38,800  +  65,000  C  +  100,000  P  +  9000 
M  +  40,000  CM. 

T.  S.  in  pounds  per  square  inch;  values  for  C,  P,  and  M  (Mn)  are 
in  percent  (not  in  hundredths  of  a  percent  as  in  Campbell's 
original  formulae). 


PHYSICAL  PROPERTIES  339 

(b)  Approximate  values  for  open  hearth  steel  unannealed: 

Acid  steel:  45,000  +  108,000  C 
Basic  steel:  45,000  +  90,000  C 

Salom's  formula  for  tensile  strength  (average  values) : 
T.  S.  =  31-74  +  70-53  C 

T.  S.   in   kilograms   per  square  millimeter;  C  =  percentage  of 
carbon. 

Sauveur's  formulae  (Metal lor gaphy,  p.  138  et  seq.): 
(a)  Tensile  strength : 

(j)  Hypo-eutectoid  steels  (carbon  not  over  0.834%) 

T.  S.  =  50,000  +  90,000  C 
(ii)  Hypsr-eutectoid  steels  (carbon  over  0.834%) 

T.  S.  =  142,000  —  20,600  C 
(6)  Elongation,  percent  in  2",  for  hypo-eutectoid  steels: 

E  =  40  -  36  C 
Thurston's  formula  for  tensile  strength  (minimum  values): 

Unannealed  steel:  T.  S.  =  42.32  +  49.37  C 
Annealed  steel:  T.  S.  =  35.27  +  42.32  C 

T.  S.  in  kilograms  per  square  millimeter;  carbon  in  percent. 

Webster's  formula  for  tensile  strength,  based  on  his  values  for 
pure  iron,  carbon,  phosphorus  and  sulphur,  may  be  stated  as 
follows : 

T.  S.  =  34,750  +  80,000  C  +  m  P  +  50,000  S 

T.  S.  in  pounds  per  square  inch;  C,  P,  and  S  in  percent;  m  a 

variable,    depending  on   the   carbon   content,   from   80,000   to 

150,000.     A  former  value  assigned  for  pure  iron  was  38,000. 

Weyrauch's  formula  for  tensile  strength  (minimum  values): 

T.  S.  =  44-17(1  +  C)j 

T.  S.  in  kilograms  per  square  millimeter;   C  =  percentage  of 
carbon. 

(2)  Structural  Formulae. — Sauveur's  formulae:  These  are 
based  on  the  assumption  that  the  tensile  strength  in  pounds  per 
square  inch  is  for  ferrite  50,000,  for  pearlite  125,000,  and  for 
cementite  5000;  the  percentage  of  elongation  in  2"  for  ferrite 
40,  and  for  pearlite  10  (no  estimate  for  cementite) : 
(a)  Tensile  strength: 

(i)  Hypo-eutectoid  steels : 

T.  S.  =  500  F  +  1250  P 
=  50,000  +  750  P 

(«)  Hyper-eutectoid  steels : 

T.  S.  =  1250  P  4-  50  Cm 
=  5000  +  1 200  P 


340  PHYSICAL  PROPERTIES 

(&)  Elongation,  percent  in  2",  for  hypo-eutectoid  steels: 

E  =  0.4  F  +  o.iP 
=  40  -  0.3  P 

F,  P,  and  Cm  =  respective  percentages  of  ferrite,  pearlite,  and 
cementite. 

Quality  Formulae. — These  are  for  the  purpose  of  comparing  the 
properties  of  a  specimen  with  a  standard,  or  of  two  or  more 
specimens  with  each  other  to  decide  their  relative  merits.  To 
illustrate  why  this  is  sometimes  desirable,  a  piece  of  steel  may  be 
likened  to  a  photographic  plate.  The  plate  is  capable  of  pro- 
ducing a  beautiful  result  provided  it  is  suitably  prepared,  properly 
exposed  and  carefully  developed;  a  mistake  in  any  one  of  these 
processes  will  result  in  a  defective  negative.  In  the  same  way, 
the  steel  if  of  suitable  composition  has  latent  possibilities  which 
can  only  be  brought  out  to  their  fullest  extent  by  the  greatest 
attention  to  every  detail  in  its  handling  and  treatment.  Ex- 
amples of  how  this  works  out  will  be  given  below.  The  figure 
used  for  the  comparison  is  termed  the  figure  of  merit,  merit 
number  or  quality  figure.  The  formulae  are  based  on  the  well- 
known  fact  that,  under  the  same  general  conditions,  as  the 
strength  increases  the  ductility  decreases,  and  vice  versa;  and 
while  the  assumption  that  they  are  inversely  proportional  is  only 
approximately  true,  and  for  limited  ranges,  the  deductions  which 
may  be  drawn  from  it  are  sufficiently  accurate  for  most  purposes. 
The  specimen  showing  the  largest  quality  figure  must  possess  the 
highest  combination  of  strength  and  ductility  and  therefore 
be  in  the  highest  state  of  development,  at  least  from  an  abstract 
viewpoint.  There  must,  however,  always  be  considered  the 
purpose  for  which  the  material  is  intended.  Thus,  a  sample 
with  very  high  strength  and  comparatively  low  ductility  might 
have  a  higher  quality  figure  than  another  sample  with  much  lower 
strength  but  higher  ductility.  For  cold  bending  or  flanging, 
the  second  would  be  the  more  suitable.  Where  the  determi- 
nations are  accurately  made,  the  value  for  the  elastic  limit 
best  represents  the  strength;  with  turned  specimens  the  reduc- 
tion of  area  is  a  more  accurate  measure  of  the  ductility  than 
the  elongation  which  is  more  likely  to  be  affected  by  the  point  of 
rupture  and  the  shape  of  the  specimen. 

De  Marre  formula:  (see  Armor  Plate,  page  8). 

British  or  English  formula : 

M  =  T  +  E 

M  =  figure  of  merit;  T  =  tensile  strength  in  gross  tons  per 
square  inch;    E  =  elongation,  percent,  for  specimens  of  iden- 
tical or  similar  shape. 
McKenna's  formula : 

M  =  T  (E  +  20) 

M  =  figure  of  merit;  T  =  tensile  strength  in  pounds  per 
square  inch;  E  =  elongation,  percent,  for  specimens  of  identical 
or  similar  shape. 


PHYSICAL  SOLUTION— PICKLING 


341 


Tiemann's  formula : 


S  X  D 


Q  =  quality  figure;  S  =  strength,  either  tensile  strength,  but 
preferably  elastic  limit  in  any  unit;  D  =  ductility,  either  elonga- 
tion, but  preferably  reduction  of  area,  percent,  for  identical  or 
similar  specimens.  As  examples  of  the  last  formula,  taking  the 
elastic  limit  as  S  and  the  reduction  of  area  as  D: 


No. 

Treatment 

Tensile 
Strength 

Elastic 
Limit 

Elonga- 
tion, % 

Reduc- 
tion of 
area,  % 

Quality 
Figure 

(E.L.XRed.) 

i 

2 
3 

4 

5 

Untreated 
Untreated 
Annealed 
Quenched  and  Tem- 
pered (a) 
Quenched  and  Tem- 
pered (6) 

80,000 
85,000 
80,000 

90,000 

100,000 

40,000 
42,000 
39,000 

55,000 
60,000 

23 

21 
25 

26 
23 

40 
36 

43 

55 
50 

1,600,000 
1,512,000 
1,677,000 

3,025,000 
3,000,000 

Nos.  i  and  2  are  taken  as  samples  of  slightly  different  compo- 
sition but  having  had  the  same  treatment;  Nos.  3  to  5,  samples  of 
the  same  composition  but  having  had  treatment  as  shown. 
,  Obstruction  Theory  (Howe,  Metallography,  389). — "The 
usual  explanation  of  the  increase  of  the  tensile  strength  and 
elastic  limit  with  the  carbon  content  is,  briefly,  that  the  stronger 
pearlite  stiffens  the  mass  by  impeding  the  flow  of  the  weaker 
ferrite;  and,  going  a  step  further,  that  the  reason  why  pearlite, 
though  made  up  of  about  6  parts  of  ferrite  to  i  of  cementite,  is 
yet  so  much  stronger  than  pure  ferrite,  is  that  this  pearlitic 
cementite  thus  stiffens  the  pearlitic  ferrite.  The  pearlite  in  one 
case  and  the  pearlitic  cementite  in  the  other,  is  said  to  "hold  up" 
the  ferrite.  After  discussing  the  "obstruction  principle"  I  call 
attention  to  the  ferrite-refinement  principle,  that  the  effects  of 
increasing  carbon  contents  may  be  due  in  considerable  part  to 
the  accompanying  changes  in  the  grain  size  of  the  ferrite."  See 
also  Conduction  (under  Heat),  page  200;  Density,  page  132;  Ex- 
pansion (under  Heat),  page  204. 

Physical  Solution. — See  page  107. 

Physical  Test. — See  page  467. 

Physically  Developed. — A  term  sometimes  applied  to  material 
whose  properties  have  been  increased  by  cold  working  (e.g.,  cold 
twisted  bars)  as  opposed  to  heat  treating. 

Physically  Dissolved. — See  page  107. 

Physico-metallurgical  (adj.). — Relating  to  physical  metallurgy, 
q.v. 

Piano  Wire  Gage. — See  page  187. 

Pickling. — The  treatment  of  iron  or  steel  with  dilute  acids  for  the 
purpose  of  obtaining  a  clean  surface  by  removing  the  scale 
(oxide).  When  the  action  is  completed  the  piece  is  washed  in 
water  (swilled)  to  free  it  from  the  adhering  acid,  and  is  sometimes 


342  PICKLING  BATH— PIG  IRON 

dipped  into  milk  of  lime  (liming)  to  eliminate  the  last  traces. 
The  pickling  fluid,  when  so  exhausted  that  it  can  no  longer  be 
used  profitably,  is  known  as  spent  acid  or  waste  liquor.  In 
Reed's  pickling  process  a  solution  of  dilute  sulphuric  acid  is  used 
and  the  object  to  be  pickled  is  made  the  cathode,  the  anode 
being  a  piece  of  lead.  Pickling  is  of  special  application  in  the 
manufacture  of  sheets  and  tin  plate  (page  431),  tubes  (page  491), 
and  wire  (page  507). 

Pickling  Bath.— See  page  507. 

Picric  Acid. — See  page 287. 

Piece. — The  particular  piece  of  metal  under  consideration,  usually 
in  connection  with  rolling  or  forging:  see  page  407. 

Pielsticker  and  Miiller  Process.— See  page  65. 

Piercing. — Producing  a  hole  in  a  body  by  forcing  a  pointed  instru- 
ment through  it,  the  displaced  material  being  forced  into  the  wall 
(distinction  from  punching). 

Pietzke  Process. — See  page  380. 

Pizeoglyps. — See  page  293. 

Piezometer. — See  page  476. 

Pig. — (i)  See  Pig  Iron;  (2)  in  the  open  hearth  process:  see  page  314. 

Pig  Back. — See  page  314. 

Pig  Bed.— See  page  36. 

Pig  Boiling.— See  page  374. 

Pig  Breaker. — A  machine  for  breaking  off  the  pigs  from  the  sow  or 
runner  in  the  case  of  sand-cast  pig  iron. 

Pig  Casting  Machine.— See  Pig  Machine. 

Pig  Face.— See  page  68. 

Pig  Iron. — Sometimes  called  pig  metal :  (i)  the  name  given  to  cast 
iron  which  is  cast  at  the  blast  furnace  into  shapes  known  as  pigs 
for  convenience  in  handling  and  transporting  after  cooling; 
(2)  also  applied  as  a  general  term  to  the  product  of  the  blast 
furnace  (either  solid  or  molten)  before  treatment  in  some  refining 
process,  or  casting  into  finished  products.  The  name  pig  is 
derived  from  the  old  method  of  casting  when  the  molten  metal 
was  led  to  the  depressions  or  molds  in  the  sand  floor  of  the  pig 
beds;  the  iron  in  the  molds  proper,  being  connected  to  that  in  the 
runner  or  feeder,  bore  a  supposed  resemblance  to  a  litter  of 
sucking  pigs,  the  runner  being  called  the  sow  (sow  metal). 
This  method  produces  what  is  known  as  sand  cast  pig.  To 
avoid  the  sand  which  always  adheres,  the  iron  is  frequently  cast 
in  metal  molds  or  chills,  and  is  then  known  as  chill  cast  pig,  or  if  a 
pig  machine  is  used,  machine  cast  pig,  or  rarely,  from  the  fact 
that  they  are  cast  individually  without  a  central  connecting 
runner,  motherless  pigs. 

The  color  of  the  fracture  of  pig  iron  depends  upon  the  con- 
dition of  the  carbon;  if  it  is  all  combined  (the  silicon  being  low) 
the  fracture  is  white  (not  silvery);  if  all  is  in  the  form  of  graphite 
it  is  gray  or  graphitic  (rarely  called  black) ;  while  if  only  a  small 
part  is  in  the  graphitic  form,  giving  rise  to  alternate  white  and 
gray  spots,  the  iron  is  said  to  be  mottled.  Johnson  has  called 
attention  to  spotted  iron  which  is  gray  on  the  outside  and  has 
white  spots  near  the  center;  this  he  explains  as  due  to  silicon 


PIG  IRON  343 

below  0.8%,  together  with  sufficiently  rapid  cooling,  the  portion 
freezing  last  at  the  center  being  composed  of  the  eutectic  segre- 
gate (Met,  &  Chem.  Eng.,  Nov.  i,  1916).  If  the  silicon  is  high 
the  fracture  is  silvery  (not  white).  Close  pig  (close  grained 
pig;  close  iron)  has  a  very  fine  grained  fracture;  open  iron  has  a 
coarse  fracture  or  grain-.  Blazed  pig,  glazed  pig,  or  glazy  pig 
(Eng.)  is  a  grade  which  is  brittle  from  high  silicon.  Cinder  iron 
or  pig  (Eng.)  is  smelted  from  a  mixture  containing  some  puddle 
cinder  or  refinery  cinder;  According  to  T.  Turner,  a  grade  with 
about  2^%  carbon,  i/^%  manganese,  and  considerable  phos- 
phorus is  common  in  South  Staffordshire.  Dry  Iron  (Eng.)  is  low 
in  silicon,  while  rich  iron  (Eng.)  or  hot  iron  is  high  in  silicon  and 
usually  low  in  sulphur.  In  foundry  work  iron  which  is  fluid, 
partly  from  its  temperature  and  partly  from  its  composition,  is 
called  hot  iron;  the  opposite  is  cold  or  dull  iron  or  metal.  Pig 
iron  suitable  for  making  pots  or  similar  objects  is  sometimes 
called  pot  metal.  Gun  metal  may  signify  either  a  kind  of  bronze, 
or  steel  or  cast  iron  suitable  for  making  cannon.  In  the  last  case 
(gun  iron)  requirements  have  been  given  as  tensile  strength 
33,000  to  35,000  pounds  per  square  inch,  with  transverse  strength 
of  4000  pounds  on  an  arbitration  bar  i^"  in  diameter,  with  12" 
between  supports.  Pig  steel  (Richards,  Eng.  Soc.  W.  Pa.,  March 
19,  1912)  is  the  name  for  the  metal  made  directly  from  iron  ore  in 
an  electric  pig  iron  furnace,  which  is  really  crude  steel  with  2.2% 
or  less  carbon,  a  very  small  amount  of  silicon  and  manganese,  low 
in  sulphur  and  phosphorus. 

Pig  iron  is  classified  according  to  (a)  the  method  of  manu- 
facture (see  Blast  Furnace);  (b)  the  purpose  for  which  it  is 
intended;  and  (c)  its  composition.  It  was  formerly  graded  by 
breaking  the  pig  and  examining  the  fracture,  but  this  method 
has  been  largely  superseded  by  chemical  analysis.  The  terms 
pig  and  iron  are  often  used  as  abbreviations  for  pig  iron,  the 
latter  where  the  context  indicates  clearly  what  is  meant. 

A.  Method  of  manufacture : 

1.  Coke  pig:  smelted  with  coke,  and  always  with  hot 

blast. 

2.  Charcoal  pig:  smelted  with  charcoal: 

(a)  Hot  blast. 

(b)  Cold  blast. 

3.  Anthracite  pig:  smelted  with  anthracite  coal  mixed 
with  coke,  and  with  hot  blast. 

B.  Purpose  for  which  intended: 

4.  Bessemer  pig:  for  the  Bessemer  process: 

(a)  Acid  (in  this  country  the  only  kind) ;  hematite 
pig  (Eng.) ;  also  used  for  the  acid  open  hearth 
process. 

(b)  Basic   (foreign);  Thomas  pig:   Thomas-Gil - 
christ  pig  (Eng.). 

5.  Basic    pig     (basic    open  hearth  pig)  for  the  basic 

process  (U.  S.),  and  for  the  basic  Bessemer  process 
(foreign). 


344  PIG  IRON 

6.  Malleable  pig,  or  malleable,  for  malleable  cast-iron 
castings. 

7.  Foundry  pig,  for  foundry  work. 

8.  Forge  pig:  an  inferior  grade  used  for  puddling  and 
for  some  classes  of  foundry  work. 

C.  Chemical  composition : 

9.  Silicon  pig  or  high  silicon  pig. 

10.  Low  phosphorus  pig. 

11.  Special  low  phosphorus  pig. 

12.  Ferro-alloys    and    special    cast  irons   (e.g.,  ferro- 
manganese) :  see  below. 

The  classification  on  the  next  page  has  been  arranged  by  Eliot 
A.  Kebler  based  on  the  Government's  scale  of  prices  (to  July  i, 
1918).  The  previous  classification  furnished  by  Mr.  Kebler  has 
been  retained  also  for  purposes  of  reference: 

(The  following  details  have  been  taken  largely  from  an  article 
by  Eliot  A.  Kebler,  of  which  the  foreign  classification  was 
supplied  by  W.  W.  Hearne,  in  the  Iron  Trade  Review,  June  25, 
1908,  entitled  "Grading  Pig  Iron,  Ferro-Alloys  and  Coke." 
This  has  been  somewhat  rearranged  and  several  additions 
made.) 

In  this  country  pig  iron  is  usually  sold  per  ton  of  2240  pounds 
(rarely  2268  pounds),  and  always  in  England;  in  Germany  and 
France  per  metric  ton  of  1000  kilograms. 

Bessemer  pig  iron : 

Standard  Bessemer  (U.  S.),  used  in  making  acid  Bessemer 
and   acid   open   hearth   steel.     The   standard  specification  is : 

Silicon i  to  2 .  oo  % 

Phosphorus,  not  over     o.oi 

Sulphur,  not  over o .  05 

In  the  central  section  (Mahoning  and  Shenango  Valleys  and 
Pittsburg)  it  is  sold  per  ton,  2268  pounds,  if  sand  cast,  or  2240 
pounds,  if  chill  cast,  except  for  special  purposes  where  the  sand 
iron  is  broken,  in  which  case  it  may  be  sold  per  ton,  2240  pounds, 
and  a  charge  of  25c.  may  be  added  for  breaking.  In  the  East 
and  West  (Chicago)  it  is  always  sold  per  ton  of  2240  pounds. 

Hematite,  also  spelled  (Eng.)  haematite  (for  acid  Bessemer 
process) : 

Silicon,  about    2 . 50  % 

Sulphur,  about    o .  035 

Phosphorus,  usually °-°3S 

seldom  running  over  0.06 

West  Coast  hematite  has  manganese  under  0.50%;  East  Coast 
hematite,  over  0.75%.  Bessemer  pig  in  Europe  generally 
should  not  contain  more  than  0.05%  phosphorus.  It  is  often 
used  as  a  synonym  for  hematite  pig,  but  while  the  latter  term 
covers  all  the  grades  from  No.  i  to  white,  the  term  Bessemer 
pig  is  applied  only  to  Nos.  i,  2,  and  3  (Ridsdale).  This  grade  of 
pig  is  also  referred  to  as  non-phosphoric. 


PIG  IRON 


345 


11 


o  w     ^-^ 

"IP 


B  a 


sfpl 

cor*  3  « 


!?U 


7  i  +++  i  +++++ 

•  3  »  .  •    °.  "•'  •  "•'  °- 

CHARCOAL, 

Southern  or  Warm  Blast  +$17  .00 
Sil  2.00  max.  P.  0.40-0.60. 
Add  $1.00  for  each  0.50  additional  Silicon. 
Cold  Blast  +$47.00 
Muirkirk  +  37  .00 
Northern  Semi-cold  Blast  +  37  .00 
Lake  Superior  for  Sil.  1.25  max.  +  2.50 

Compiled  by  ELIOT  A.  KEBLER. 

* 

'.  g 

:8.  . 

•CO 

• 

;W        :  : 

:W           ^M 

:<        :g 

FOUNDRY  IRON  (All  Sulphur  under  0.05) 

Manganese,  % 

foiS  B  c  cs^»«2  8  d"o  6  c 

LOW  PHOSPHORUS. 
Silicon  not  over  2.00.  Sulphur  not  over  0.04. 

o 

ooooooooooo 

OwtOOOOO^^OCI 

:or  each  i  %  addition  of  Silicon. 

Coppe 
over  o 

O  00  t-  v>  fO  i-i  OiO  *f)  if)  M 

4* 

0 

n 

o 

§o«/-.  oooooo 

If 

§O 
10 

I-i  O\OO  i«  PO  i-i  O\VO  "5  IO  H 
M* 

§ 

0 
M 

o  o  »/>o  o  o  o  o  o 

H 

|a 

§O 
«fl 

JOirtOOOOOO 
O>O  rfN  Oi\O  V)\f)n 

?+++++++! 

M 

O 
1/J 

o 

M 

SS^SSS0,0,0, 

3| 

0 

§£ 

f<5  w 

M    M 
++- 

ooooooooo 

f-H-++++++ 

V) 

O  0  M  cOfJO  t-CX)  Oi 

TI  ° 

s   • 

O        lOOOOOOO 
«T  HjMOOOOOO 

0  S  H  r<i  uio  r-^oo  a 

a 

r 

0  O  O  O  0  O  "§  0  O  O  2 

ooooooooooo 

SILVERY 

0  0  0  O  0 
0  O  «/5  tOO 

0  i-i  roiAoo 

000 
O  POO 

'Z          •    •    • 

0,0        ^^« 
WM         +++ 

Add  $3.  oo  for  each 
additional  unit  of  Silicon. 

I    !    !    '.       '.'.'.'. 

.    .    .    .       .    .    .   . 

+++4-+ 

d 

8 

CO 

^u,  ,*  ,0^.00 

§8§§§ 

O  1^-00  O  O 

Wco 

%z 
%%   §§§ 

w       •  •  • 

fe            2«2 

O  \f.ir>tf.  if)  if.  if)  if>  tf. 

HHNN^fOTrTtl° 

346  PIG  IRON 

Thomas-Gilchrist  or  Thomas  pig  iron  (for  the  basic  Bessemer 
process)  is  usually  about : 

Silicon 0.50% 

Phosphorus    2 . 50 

Manganese 2 . 50 

Sulphur,  up  to 0.20 

In  England  and  on  the  Continent  basic  pig  (phosphoric  or 
phosphoretic  pig)  is  regarded  as  containing  1.5  to  3%  phos- 
phorus, 0.10%  or  less  sulphur,  1.5  to  2.5%  manganese,  and  less 
than  i%  silicon  (Ridsdale). 

Malleable  Bessemer  or  malleable  iron  (also  called  coke 
malleable  or  malleable  coke  iron),  used  for  the  manufacture 
of  malleable  cast-iron  castings:  the  usual  specification  is: 

Phosphorus,  not  over o.  20% 

Sulphur,  not  over o .  05 

Silicon,  as  specified o .  75  to  2 .  oo 

If  sand  cast,  pigs  are  usually  broken,  and  both  sand  cast  and 
chill  cast  are  sold  per  ton  of  2240  pounds,  except  from  a  few 
furnaces  in  the  Central  District  which  still  sell  some  broken 
and  unbroken  pigs  per  ton  of  2268  pouuds. 

Low  phosphorus  pig  (U.  S.),  sometimes  called  special  low 
phos  (for  making  steel  extra  low  in  phosphorus):  the  usual 
specification  is : 

Silicon i  to  2 . 00% 

Phosphorus,  not  over 0.035 

Sulphur,  not  over 0.035 

Higher  silicon  is  desired  when  for  use  in  baby  Bessemer  con- 
verters. 

Washed  metal  (see  page  383)  is  pig  iron  from  which  most 
of  the  silicon  and  phosphorus  have  been  removed  (for  special 
low  phosphorus  steel:  open  hearth  and  crucible  process);  it 
is  sold  by  analysis,  the  four  analyses  recognized  (U.  S.)  being: 

1.  Phosphorus,  not  over    0.010% 

Sulphur,  not  over    0.015 

2.  Phosphorus,  not  over    0.015 

Sulphur,  not  over    o .  020 

3.  Phosphorus,  not  over    0.020 

Sulphur,  not  over    0.025 

4.  Phosphorus,  not  over    0.025 

Sulphur,  not  over    o .  030 

It  is  cast  on  an  iron  plate,  and  comes  in  irregular  pieces  about 
8"  square;  sold  per  ton  of  2240  pounds. 

Basic  pig;  basic  iron  (U.  S.),  for  the  basic  open  hearth 
process;  the  specifications  are: 

Silicon,  under    i .  oo 

Sulphur,  under    0.05 

The  phosphorus  is  not  specified  but  is  usually  under  0.50%, 


PIG  IRON  347 

except  with  some  Southern  irons,  when  it  may  go  as  high  as 
1.00%.  It  is  sold  per  ton  of  2 240  pounds.  In  Europe  or  England 
there  is  practically  no  open  hearth  basic  pig  made;  at  Middles- 
boro,  Bell  Bros,  are  making  a  grade  which  analyzes: 

Silicon 0.75  to  1.50% 

Phosphorus i .  oo  to  i .  75 

Sulphur,  up  to o .  20 

American  foundry  iron :  graded  by  fracture  (this  method  is 
being  rapidly  superseded  by  analysis  grading) : 

No.  i  Foundry :  Fracture  contains  crystals. 

No.  2  Foundry :  This  is  considered  the  standard  and  contains 
medium-size  crystals,  say  %"  square,  with  no  spot  larger  than 
i"  in  diameter  without  crystals,  although  the  pig  can  be  close 
for  }/±'  along  the  edges. 

No.  3  Foundry:  Contains  small  crystals;  fracture  close. 

East  of  Altoona,  Pa.,  and  throughout  all  of  New  York  these 
grades  are  No.  i  X,  No.  2  X,  No.  2  Plain,  and  No.  3  Foundry. 
No.  i  is  the  highest  in  price,  the  usual  differential  being  50 
cents  a  ton. 

Forge  has  a  gray  fracture  with  practically  no  crystals. 

Mottled  shows  small  white  spots  giving  the  fracture  a  mottled 
appearance;  most  of  the  carbon  is  in  the  combined  state. 

White  shows  a  white  fracture  as  practically  all  the  carbon 
is  in  the  combined  state.  These  last  two  grades  are  usually 
high  in  sulphur  and  low  in  silicon. 

In  the  South  (U.  S.)  iron  which  has  a  silvery  fracture  is  graded 
as  follows: 

Silvery  iron  or  silvery  gray  iron  is  sometimes  divided  into: 
No.  i  Silvery,  usually  about  5  %  of  silicon. 
No.  2  Silvery,  usually  about  4%  of  silicon. 

No.  i  Soft :  Solid  same  price  as  No.  i  Foundry. 

No.  2  Soft:  Solid  same  price  as  No.  2  Foundry. 

No.  4  Foundry:  Price  is  between  that  of  No.  3  Foundry  and 
Gray  Forge. 

Foundry  iron  containing  6  to  12%  of  silicon  is  called  high 
silicon  softener  or  softener,  or  is  designated  by  the  content, 
e-g-,  "8%  silicon,"  etc. 

Foundry  pigs  cast  in  sand  are  always  broken,  and  the  product 
of  all  furnaces  outside  of  a  few  in  the  Central  District  is  sold 
per  ton  of  2240  pounds.  These  few  still  sell  per  ton  of  2268 
pounds,  the  extra  28  pounds,  being  added  to  cover  sand  adhering 
to  the  pig.  Forge,  mottled,  and  white  irons  may  be  broken 
or  unbroken  and  are  sold  per  ton  of  2240  pounds,  with  the  excep- 
tion of  some  Central  District  irons  which  are  sold  per  ton  of 
2268  pounds.  No.  2  Foundry  and  No.  2  X  Foundry  are  the  stand- 
ards, and  No.  2  Soft  sells  at  the  same  price.  No.  i  Foundry 
or  No.  i  Soft  sells  usually  for  50  cents  a  ton  higher,  depending 
upon  the  silicon  content.  The  other  grades  decrease  25  to 
50  cents  a  grade.  Scotch  indicates  a  more  fluid  iron,  usually 
higher  in  phosphorus  and  silicon  than  the  ordinary  furnace 
run:  the  higher  the  silicon  the  higher  the  price.  In  selling  by 


PIG  IRON 


analysis  the  tendency  is  to  do  away  with  numbers  and  merely 
give  the  limits  in  silicon  and  sulphur. 

American  Foundry  and  Forge  Iron  Graded  by  Analysis:  A 
committee  appointed  by  the  blast  furnace  interests  has  made 
the  following  classification  by  analysis,  and  the  tendency  is 
to  sell  iron  by  analysis  instead  of  by  fracture.  All  pig  iron 
cast  in  chills  is  sold  by  analysis,  per  ton  of  2240  pounds. 


SOUTHERN  POINTS 

Silicon,  %  Sulphur,  % 

No.  i  Foundry 2 . 75  to  3 . 25  o .  05    and  under 

No.  2  Foundry 2 .  25  to  2 . 75  o .  05    and  under 

No.  3  Foundry i .  75  to  2 . 25  o .  06    and  under 

No.  4  Foundry i .  25  to  2 .  oo  o .  065  and  under 

Gray  Forge i .  25  to  i .  75  0.07    and  up 

No.  i  Soft 3 .  oo  and  over  o .  05    and  under 

No.  2  Soft 2 . 50  to  3 . 25  o .  05    and  under 

EASTERN  POINTS 

Silicon,  %  Sulphur,  % 

No.  i  X 2.75  and  up  o .  03    and  under 

No.  2  X  Foundry  2 . 25  to  2. 75  0-045  and  under 

No.  2  Plain i .  75  to  2 . 25  o .  05    and  under 

No.  3  Foundry i .  25  to  i .  75  o .  065  and  under 

No.  2  Mill 1.25  and  under  o .  065  and  under 

Gray  Forge i . 50  and  under  0.065  and  up 

NOTE. — If  sulphur  is  in  excess  of  maximum,  the  iron  is  graded 
as  lower  grade,  regardless  of  silicon. 

CENTRAL  WEST  AND  LAKE  POINTS 

Silicon,  %  Sulphur,  % 

No.  i  Foundry 2 . 25  to  2 . 75  0.05  and  under 

No.  2  Foundry i .  75  to  2 . 25  o  .05  and  under 

No.  3  Foundry 1.75  and  under  -o .  05  and  under 

Gray  Forge o .  05  and  over 

BUFFALO  DISTRICT 

Silicon,  %  Sulphur,  % 

Scotch 3  •  oo  and  over  0.05  and  under 

No.  i  X 2 . 50  to  3 .  oo  o .  05  and  under 

No.  2  X 2 .  oo  to  2 . 50  o .  05  and  under 

No.  2  Plain i .  50  to  2 .  oo  o .  05  and  under 

No.  3  Foundry i . 50  (under)  0.05  and  under 

Gray  Forge o .  05  (over) 


PIG  IRON  349 

CHICAGO  POINTS 

Silicon,  %  Sulphur,  % 

No.  i  Foundry 2 . 25  to  2 . 50  o .  02  to  o .  05 

No.  2  Foundry 1.75102.25  0.02100.05 

No.  3  Foundry i  .35  to  i .  75  0.06  and  under 

Scotch 2 . 50  to  3 .  oo  o .  05  and  under 

Silvery 3 .00  to  3 . 50  0.05  and  under 

Gray  Forge o .  06  and  over 

Sampling. — The  American  Society  for  Testing  Materials 
recommended  the  following  method  of  sampling  which  has 
been  adopted  by  the  American  Foundrymen's  Association. 
In  all  contracts  where  pig  iron  is  sold  by  chemical  analysis 
each  carload  or  its  equivalent  shall  be  considered  as  a  unit. 
At  least  one  pig  shall  be  selected  at  random  from  each  four 
tons  of  every  carload,  and  so  as  fairly  to  represent  it.  Drill- 
ings shall  be  taken  so  as  fairly  to  represent  the  fracture  surface 
of  each  pig  and  the  sample  analyzed  shall  consist  of  an  equal 
quantity  of  drillings  from  each  pig,  well  mixed  and  ground 
before  analysis.  In  case  of  disagreement  between  buyer  and 
seller,  an  independent  analyst,  to  be  mutually  ^  agreed  upon, 
shall  be  engaged  to  sample  and  analyze  the  iron.  In  this 
event  each  pig  shall  be  taken  to  represent  every  two  tons. 
The  cost  of  this  sampling  and  analysis  shall  be  borne  by  the 
buyer  if  the  shipment  is  proved  up  to  specification,  and  by 
the  seller  if  otherwise. 

English  Foundry  Iron. — This  is  graded  by  fracture,  and  no 
analysis  is  guaranteed.  The  rules  for  standard  foundry  pig 
iron  issued  by  the  London  Metal  Exchange  are  as  follows,  and 
it  will  be  noted  that,  instead  of  grading  by  silicon  content,  as 
in  this  country,  sulphur  seems  to  be  the  governing  element: 

Silicon,  %       Phosphorus,  %  Sulphur,  % 

No.  i 2>£  to  3^  i. oo  0.04 

No.  2 2^  to  3^  1.25  0.05 

No.  3 i  not  over  3)^  1.65  0.08 

No.  4 i  not  over  3  i . 75  o.  10 

The  ordinary  English  pig  irons  can  be  divided  into  two  groups, 
with 

Manganese,  under  0.75%,  and 
Manganese,  say,  0.75  to  1.10%. 

The  brand  and  grade  chiefly  imported  into  this  country  is 
Middlesboro  No.  3 ;  analysis  unguaranteed,  but  usually 

Phosphorus i . 40  to  i .  50% 

Manganese 0.40  to  0.75 

Silicon,  usually  high,  say 2 . 50 

Sulphur , o .  02  to  o .  05 

No.  i  has  practically  the  same  composition  except  that  the 
sulphur  is  extremely  low. 


350  PIG  IRON 

All  mine  pig,  mine  pig,  or  ore  metal  (Eng.)  is  made  from  ore 
without  any  admixture  of  scale  or  cinder;  its  composition  is 
about  as  follows : 

Phosphorus o. 20  to  o. 70% 

Sulphur o .  06  to  o .  20 

Manganese,  under o.  75 

Scotch  iron  is  also  sold  by  fracture,  a  typical  analysis  of 
No.  3  being: 

Phosphorus 0.60  to  1.15% 

Manganese. i .  10  to  i .  80 

Sulphur,  about o .  03 

Silicon,  about 2 .00  to  2 . 50 

American  Charcoal  Irons.— These  irons  are  divided  into 
two  classes: 

(a)  Cold  blast,  which  is  made  in  small  furnaces  with  a 
capacity  of  about  4  to  8  tons  a  day,  blown  with  un- 
heated  air,  and 

(&)  Warm  blast,  in  which  the  blast  is  preheated  to  from 
500°  to  900°  F.  (260°  to  480°  C.). 

Cold  blast  charcoal  iron  (used  principally  for  making 
chilled  rolls),  outside  of  the  Lake  Superior  region,  is  graded  as 
follows: 

No.  i,  highest  silicon,  lowest  sulphur  iron,  with  a  fracture 
like  that  of  a  No.  3  coke  iron. 

No.  2  has  a  fracture  like  that  of  a  Forge,  and  will  chill  %"  deep 
when  cast  against  an  iron  plate.  Casting  such  an  iron  on  an  iron 
plate  to  determine  the  depth  of  chill  is  called  the  chill  test.  What 
is  termed  a  paper  chill  is  where  a  line  of  white  no  thicker  than  a 
piece  of  paper  is  visible  around  the  edge  of  the  pig  (Johnson). 

No.  3  shows  Y±'  chill. 

No.  4  a  %"  to  K"  chill. 

No.  5  a  %"  to  i%"  chill,  the  face  of  the  pig  being  strongly 
mottled. 

No.  6  is  white,  practically  all  of  the  carbon  being  in  the  com- 
bined state. 

Warm  blast  or  hot  blast  charcoal  iron  (used  principally  for 
car-wheel  work,  for  strengthening  general  machinery  castings, 
and  for  making  rolls),  outside  of  the  Lake  Superior  region,  is 
graded  as  follows: 

No.  i,  highest  silicon,  lowest  sulphur  iron,  with  a  fracture 
like  that  of  No.  2  coke  iron. 

No.  2  has  a  fracture  like  that  of  a  No.  3  coke  iron. 

No.  3  has  a  fracture  similar  to  that  of  Forge. 

No.  4  will  show  a  chill  about  K"  deep  if  cast  against  an  iron 
plate. 

No.  5,  a  chill  about  M"  to  %". 

No.  6,,a  chill  of  about  %"  to  iK",  and  is  mottled  when  cast  in 
sand. 

No.  7  has  a  white  fracture;  the  carbon  is  practically  all  com- 
bined. 


PIG  IRON 


351 


Lake  Superior  charcoal  irons  are  graded,  not  by  fracture, 
but  by  analysis,  the  following  classification  being  most  gener- 
ally used: 

SILICON,  % 

Average 

Min. 

Max. 

Chill 

A  Scotch  

2.50 

2.38 

2.62 

B  Scotch  

......      2.25 

2.13 

2-37 

C  Scotch 

2    OO 

1.88 

2.12 

Low  i  

I  .7C 

1.63 

1.87 

High  i  

*:*    f  V 

I  .50 

1.38 

1.62 

Low  2  

I  .  25 

i  .  13 

1,37 

High  2  

I  .  OO 

0.88 

I  .  12 

T    ° 
Low  3 

07=; 

o  63 

0.87 

Trace  to  y±' 

High  * 

o  ^6 

w  •  WO 

O.  tJO 

o.  62 

VA"  tO  %" 

Low  4  

o  .  44 

v     Ov 

0.38 

0.50 

%"  to  i" 

High  4  

0.32 

0.25 

0.38 

i  "to  iH" 

Low  5  

o.  20 

0-15 

0.25 

Low  mottled 

Highs  

O.  IO 

0.05 

0-15 

White  mottled 

No.  6.., 

o.oo 

0.00 

o.os 

White 

Phosphorus 

Manganese 

Sulphur 


0.15  to  0.22% 
o .  30  to  o .  70 
trace  to  0.018 


Ferro-alloys,  ferro -products,  special  cast  irons,  or  alloy  cast 
irons. — These  are  alloys  or  metallic  compounds  of  iron  with  a 
considerable  amount  of  some  special  element  or  elements  (alloy 
elements),  such  as  manganese,  chromium,  etc.,  and  contain,  as  a 
rule,  an  equal  or  greater  amount  of  carbon  than  ordinary  pig 
iron,  this  last  differentiating  them  from  special  steels  (?.».), 
although  the  dividing  line  is  not  always  sharply  drawn.  Howe 
suggests  (E.  &  M.  J.,  1911)  as  definitions  for  ferro-alloy:  "An 
alloy  of  iron  with  so  large  a  proportion  of  some  element  other 
than  carbon  that  it  is  not  usefully  malleable  at  any  temperature." 
or  "Iron  so  rich  in  some  element  other  than  carbon  that  it  is  used 
as  a  vehicle  for  introducing  that  element  in  the  manufacture  of 
iron  or  steel."  Tiemann  has  suggested  that  ordinary  pig  iron,  as 
the  initial  member  of  the  ferro-alloy  series,  corresponding  to 
ferro-manganese,  etc.,  be  designated  as  ferro-carbon.  Owing 
to  the  fact  that  many  of  the  ferro-alloys  have  been  in  use  for  only 
a  comparatively  short  time,  fixed  standards  have  not,  in  many 
cases,  been  accepted.  One  company  designates  its  material 
by  showing  the  number  of  units  of  carbon  by  "X,"  and  the 
kind  of  alloy  by  its  chemical  symbol;  thus:  a  ferro-chrome  con- 
taining 9.70%  of  carbon  would  be  designated  "gXCr."  All 
foreign  ferro-alloys  are  sold  to  the  American  consumers  'f.o.b. 
cars  American  seaboard,  based  on  existing  duties,  United  States 
Custom  House  weights  at  seaboard  to  govern  settlement,  and 
certificate  of  foreign  chemist  of  repute  to  be  conclusive  as  to 
quality. 

Ferro-aluminumlis  sold  containing  10%  aluminum.    Metallic 


352  PIG  IRON 

aluminum  comes  in  two  grades:  No.  i  being  guaranteed  over 
99%,  and  No.  2,  over  90%  pure  aluminum,  with  no  impurities 
rendering  it  unsuitable  for  alloying  with  iron  or  steel.  Each 
grade  is  sold  by  the  pound. 

Ferro-chrome,  ferro-chromium,  or  chromeisen  runs  60  to 
68%  of  chromium.  It  is  graded  per  unit  of  chromium  and  per 
unit  of  carbon,  the  price  increasing  with  the  chromium,  and 
decreasing  with  the  increase  in  carbon,  the  percentage  of  these 
elements  being  guaranteed.  If  low  in  carbon  it  is  sometimes 
called  mild  ferro-chrome.  It  is  sold  per  ton  of  2240  pounds.  A 
typical  analysis,  guaranteed  only  as  above,  is  as  follows: 


Mild,  %  Ordinary,  % 

Chromium 64.80  66.00 

Iron 33-43  21.91 

Carbon 1-21  9.90 

Silicon o .  29  i .  40 

Phosphorus 0.027  0.07 

Sulphur 0.02  0.22 

Manganese o .  09  o .  20 

Copper 0.12  

Aluminum .... 

Eerro-chrome  is  manufactured  in  an  electric  furnace  which  may 
be  of  several  types,  such  as  a  Heroult  or  a  Girod  furnace  as  used 
for  making  steel.  The  charge  consists  of  chromite  and  anthra- 
cite coal  mixed  in  proportions  based  on  theoretical  calculations. 
In  one  operation  direct  from  ore,  ferro-chrome  with  as  low  as  5  % 
carbon  can  be  made  economically;  and  it  is  possible  to  produce  it 
with  as  little  as  2%.  The  refining  of  high  grade  ferro-chrome 
is  carried  on  in  an  arc  furnace,  where  the  alloy  is  subjected  to 
prolonged  heating  with  a  slag  of  chromite,  lime  and  flourspar. 
In  this  way  the  carbon  can  be  reduced  from  10  to  0.25%  but 
more  usually  about  0.50%.  The  content  of  chrome  remains 
about  the  same,  and  the  silicon  may  be  reduced  to  about  0.2% 
(Keeney,  Am.  Electroch.  Soc.,  XXIV). 

Ferro-manganese  contains  over  30%,  usually  over  60%, 
manganese.  Standard  ferro-manganese  is  guaranteed  only  to 
average  80%  or  over  of  manganese.  The  English  grade  runs 
lower  in  phosphorus  than  that  from  the  Continent.  It  is  sold 
per  ton  of  2240  pounds.  A  typical  analysis,  manganese  only 
guaranteed,  is: 

American,  % 
80.20 
12. 18 
0.66 
o.  16 
trace 
6.80 


I 

Manganese  

Inglish,  % 
80.50 

Iron,  by  difference.  . 
Silicon  

11.50 
1.65 

Phosphorus  
Sulphur  

0.23 

Carbon.  . 

6.78 

PIG  IRON  353 

Ferro -molybdenum  is  sold  per  pound  of  pure  molybdenum 
contained,  regardless  of  the  percentage  of  other  constituents. 
Thus,  if  a  pound  of  80%  ferro-molybdenum  is  purchased,  i>^ 
pounds  of  alloy  will  be  received.  A  typical  analysis,  molybdenum 
only  guaranteed,  is: 

Molybdenum 79-5% 

Iron 17-55 

Carbon. 3 . 24 

Phosphorus o .  028 

Sulphur 0.021 

It  is  generally  manufactured  in  the  electric  furnace  from  raw 
sulphide  ore  (molybdenite);  also  by  reduction  of  the  roasted 
sulphide  with  carbon  in  a  crucible  or  the  electric  furnace  (Keeney). 
Ferro-nickel  is  made  with  25,  35,  50,  or  75%  of  nickel  as 
specified.  The  percentage  of  the  other  constituents,  exclusive 
of  the  iron,  is  approximately: 

Carbon o .  85  % 

Silicon o. 25 

Sulphur. o.  15 

Phosphorus o .  025 

Nickel,  metallic  nickel,  or  ingot  nickel,  as  ordinarily  used  in 
the  manufacture  of  nickel  steel,  is  guaranteed  over  99%  nickel, 
and  is  sold  by  the  pound. 

Ferro-phosphorus  contains  over  10%  of  phosphorus.  It  is 
sold  per  ton  of  2240  pounds.  The  foreign  is  guaranteed  22  to  24%. 
A  typical  analysis  of  the  foreign  product,  phosphorus  only 
being  guaranteed,  is: 

Phosphorus ~  21 .40% 

Iron .- 75-03 

Manganese o.  70 

Silicon i .  63 

Carbon 1.17 

The  domestic  is  guaranteed: 

Phosphorus 18  to  22 .00% 

Sulphur,  under. o . 05 

Manganese,  under o .  50 

Pftospho -manganese  is  essentially  a  ferro-manganese  con- 
taining a  high  percentage  of  phosphorus.  It  is  sold  per  ton  of 
2240  pounds.  A  typical  analysis  shows  approximately: 

Manganese 65 .00% 

Phosphorus 25 .  oo 

Iron 7.00 

Carbon 2.00 

Silicon i .  oo 

23 


354  PIG  IRON 

Ferro-silicon,  siliconeisen,  or  high  silicon  pig  is  used  in  the 
manufacture  of  steel  to  increase  the  silicon.  It  is  usually 
called  Bessemer  ferro-silicon  (sometimes  ordinary  fem>- 
silicon)  as  the  American  is  guaranteed  not  over  0.10%  of  phos- 
phorus, and  not  over  0.05%  of  sulphur,  and  the  foreign,  while 
not  guaranteed,  is  approximately  the  same.  The  silicon  is 
10  to  20%,  usually  12%,  the  price  increasing  about  $1.00  a 
ton  per  unit.  It  is  sold  per  ton  of  2240  pounds.  A  typical 
analysis  shows: 

Silicon 12.74% 

Phosphorus o .  095 

Manganese 0.87 

Sulphur 0.02 

Ferro-silicon  higher  than  this  is  produced  in  the  electric  furnace, 
and  ordinarily  contains  over  40%  of  silicon,  and  is  known  as 
special  ferro-silicon  or  special  high  silicon  iron.  It  is  guar- 
anteed 50.%  silicon,  with  a  variation  in  price  of  $1.75  per  unit 
either  way.  The  other  constituents  are  not  guaranteed.  A 
typical  analysis  shows: 

Silicon 49 . 90% 

Manganese 0.016 

Carbon.- °-S5 

Phosphorus , 0.075 

Sulphur 0.018 

There  is  also  a  grade  guaranteed  to  average  75%  of  silicon, 
with  a  variation  in  price  of  $2.50  per  unit  either  way. 

Silico -Spiegel  is  a  product  of  the  blast  furnace.  It  contains 
17  to  22%  of  manganese  and  6  to  12%  of  silicon.  It  is  sold 
per  ton  of  2240  pounds.  The  standard  is  guaranteed: 

Manganese 18  to  20% 

Silicon 9  to  n,  average  10% 

A  typical  analysis,  nothing  but  manganese  and  silicon  guar- 
anteed, shows:  • 

Manganese "20.32% 

Iron,  by  difference 68.02 

Silicon 10 . 33 

Carbon i .  26 

Phosphorus 0.07 

Sulphur 

Silico-ferro-manganese  or  silico -manganese  is  the  name  usually 
applied  when  higher  in  manganese:  Manganese  about  60  to  80%, 
silicon,  20  to  25%,  and  varying  percentages  of  carbon,  iron,  and 
aluminum.  There  are  three  silicides  of  manganese  recognized: 
SiMn,  SiaMns,  and  Si2Mn. 

Silicon-calcium-aluminum  has  been  tried  as  a  deoxidizer;  it  is 
reported  to  consist  of  approximately: 

Silicon 47  to  57% 

Calcium 15  to  25 

Aluminum 2 . 5  to  6 . 5 


PIG  IRON  355 

Ferro-sodium  is  obtained  by  dissolving  metallic  sodium  in 
molten  pig  iron  in  a  crucible.  It  is  sold  per  pound,  and  usually 
contains  25%  of  sodium,  free  from  lime  or  excess  of  carbon. 

Spiegel,  spiegeleisen,  mirror  iron,  or  specular  pig  iron,  is  a  prod- 
uct of  the  blast  furnace.  It  contains  10  to  30%  of  manganese. 
It  is  sold  per  ton  of  2240  pounds,  and  the  standard  is  guaranteed: 

Manganese 18  to  22%,  average,  20% 

Phosphorus,  not  over o.  10 

The  silicon  limits  are  sometimes  specified.  A  typical  analysis, 
guaranteed  only  as  above,  shows: 

Manganese 20.50% 

Iron 73 . 61 

Silicon 0.76 

Carbon 5.18 

Sulphur. o .  002 

Phosphorus o .  055 

Ferro -titanium  is  produced  in  the  blast  furnace  or,  for  higher 
grades,  in  the  electric  furnace.  The  lower  alloy  contains  10 
to  12%,  is  guaranteed  only  for  titanium,  and  is  sold  per  pound 
of  alloy.  A  typical  analysis  shows: 

Titanium 11.21% 

Iron,  by  difference 87 . 68 

Carbon 0.67 

Silicon 0.37 

Phosphorus o .  04 

Sulphur o .  03 

If  higher  in  titanium,  it  is  sold  per  pound  of  pure  titanium 
contained,  regardless  of  the  percentage  of  other  constituents, 
the  titanium  alone  being  specified.  A  typical  analysis  shows: 

Titanium 51 . 30  % 

Iron 44.18 

Carbon 2.82 

Manganese o .  08 

Arsenic 1.12 

Sulphur o .  047 

Phosphorus 0.021 

Aluminum 0.41 

Ferro -tungsten  is  sold  per  pound  of  tungsten  contained,  the 
price  increasing  with  the  increase  in  tungsten,  and  decreasing 
with  the  increase  in  carbon.  Typical  analyses,  the  tungsten 
and  carbon  only  being  guaranteed,  show: 

Tungsten 85.47%  61.20% 

Iron 13-90  33-02 

Carbon o .  30  2.97 

Silicon 0.13  0.47 

Manganese o .  09  i .  88 

Aluminum o.oo  0.31 

Phosphorus 0.019  o .  03 

Sulphur 0.025  0.03 


PIG  IRON— PINCH  BAR 

It  is  manufactured  from  ores  in  three  ways:  (i)  by  direct 
reduction  by  carbon  in  a  crucible;  (2)  by  reduction  in  an  electric 
furnace  by  some  reducing  agent  other  than  carbon;  (3)  by  direct 
reduction  by  carbon  in  an  electric  furnace  (Keeney). 

Ferro-vanadium  is  sold  per  pound  per  unit  of  vanadium 
contained,  i.e.,  if  the  alloy  contains  20%  of  vanadium, .  and 
the  selling  price  is  5C.  per  unit,  it  would  cost  $1.00  per  pound, 
of  alloy.  A  typical  analysis,  vanadium  alone  being  guaranteed, 
shows : 

Vanadium 36.00% 

Manganese o .  60 

Iron 61 .00 

Carbon o .  40 

Silicon 0.90 

Aluminum o .  80 

It  may  be  produced  by  the  thermit  process;  by  reduction  of  the 
oxide  with  carbon;  or  by  reduction  of  vanadate  of  iron  with 
carbon  in  a  crucible.  In  Europe  some  is  made  by  the  reduction 
'of  the  oxide,  sulphide,  or  vanadate  of  iron  with  carbon  in  an 
electric  furnace  (Keeney). 

Pig  Iron,  Sampling  of. — See  page  349. 

Pig  Machine. — An  appliance  for  the  continuous  casting  of  pig 
iron  in  iron  molds.  The  types  at  present  in  use  consist  of  one  or 
more  endless  strings  or  strands  of  molds  mounted  on  vertically 
revolving  drums.  The  metal  is  run  into  the  molds  from  a  ladle 
at  one  end,  and  is  rapidly  cooled  with  water  as  the  molds  advance, 
so  that  the  pigs  are  cold  enough  to  be  dumped  into  a  car  or  other 
receptacle  when  they  reach  the  other  end.  In  another  type, 
formerly  used,  the  molds  were  mounted  on  a  large  horizontally 
revolving  table. 

Pig  Metal. — See  page  342. 

Pig  and  Ore  Process. — (i)  Crucible  process:  see  page  113;  (2) 
open  hearth  process:  see  page  310. 

Pig  and  Scrap  Process. — (i)  Crucible  process:  see  page  113;  (2) 
open  hearth  process:  see  page  310. 

Pig  Steel. — See  page  343. 

Pig  Up.— See  pages  314  and  393. 

Pig  Washing  Processes. — See  page  383. 

Pigging. — In  open  hearth  practice:  see  page  314. 

Pigment. — See 'page  365. 

Pile. — (i)  A  type  of  furnace:  see  page  181;  (2)  in  connection  with 
puddling,  etc.:  see  page  377. 

Pilger  Rolls. — See  page  490. 

Pill  Heat. — See  page  257. 

Pillaring.— See  page  35. 

Pin  (Eng.). — Housing  screw:  see  page  403. 

Pin  Bottom. — See  page  17. 

Pin  Hole.— See  page  113. 

Pinacoidal  Cleavage. — See  page  124. 

Pinch  Bar. — A  crowbar;  also  a  special  form  for  moving  cars  by  pry- 
ing the  wheels. 


PINCH  PHENOMENON— PITCH   DIAMETER      357 

Pinch  Phenomenon. — In  electricity:  see  page  158. 

Pinch  Roll. — See  page  415. 

Pinched  Sheet ;  Pincher. — See  page  430. 

Pine  Tree  Crystal.— See  page  122. 

Pinhead  Blister.— See  Blister. 

Pinion ;  Pinion  Housings. — See  page  407. 

Pink  Method. — See  page  61. 

Pinny  (Eng.). — A  term  used  to  describe  metal  which  contains 
enclosed  particles  of  metal  harder  than  the  rest. 

Pintsch  Gas.— See  Oil  Gas. 

Pipe;  Piping.— (i)  A  defect  in  castings:  see  page  53;  (2)  tubes: 
see  page  489. 

Pipe  Metal. — An  alloy  of  lead  and  tin  used  for  making  organ  pipes. 

Pipe  Ore. — See  page  244. 

Pipe  Stove. — See  page  34. 

Piping  Steel.— See  page  55. 

Pisolitic  Ore. — See  page  244. 

Pistol. — For  metal  spraying:  see  page  373. 

Pistol-Pipe  Stove. — See  page  34. 

Pit. — A  depression  in  the  surface  of  material  caused  (a)  by  subcu- 
taneous blowholes  from  which  the  skin  has  been  burned  away, 
and  (b)  from  scale  or  dirt  rolled  or  forged  in,  and  which  has 
subsequently  dropped  out.  Where  the  skin  from  a  blowhole  has 
not  entirely  burned  away  but  is  not  welded  to  the  rest  of  the 
metal  and  may  be  removed  by  hammering  the  piece,  it  is  called 
a  scab,  shell  or  spill  (Eng.),  and  the  material  is  said  to  be  scabby, 
shelly  or  spilly.  When  this  occurs  in  the  tread  of  car  wheels 
(usually  cast  iron),  i.e.,  when  particles  of -the  metal  drop  out 
leaving  a  hole  resembling  a  carbuncle,  it  is  known  as  shelling  or 
shelling  out ;  the  flaking  out  of  material  in  steel  wheels  is  sometimes 
similarly  designated  but  more  commonly  as  spalling  or  sometimes 
scaling.  A  defect  sometimes  occurs  in  cast  iron  wheels  which 
have  become  worn  through  the  chill,  and  have  fine  cracks  present- 
ing an  appearance  somewhat  like  that  of  a  comb,  hence  such 
wheels  would  be  called  comby.  (2)  An  excavation  to  receive 
cinder,  or  in  which  molds  are  placed. 

Pit  Annealing.— See  page  58. 

Pit  Casting. — See  page  57. 

Pit  Coal.— See  Coal. 

Pit  Healing  Furnace.— See  page  184. 

Pit  Hole.— See  Pit. 

Pit  Sample. — See  page  82. 

Pit  Scrap. — The  steel  which  has  run  into  the  cinder  pit  under  the 
ladle  when  a  heat  is  tapped. 

Pitch. — (i)  The  height  of  the  top  of  an  arch  above  the  points  from 
which  it  springs;  (2)  the  distance  between  two  consecutive  threads 
of  a  screw  measured  on  a  line  parallel  to  the  axis,  or,  in  other 
words,  the  amount  the  screw  would  be  raised  by  one  complete 
revolution;  (3)  a  thick,  sticky,  black  substance  obtained  from  the 
sap  of  pine  trees,  or  by  the  distillation  of  coal. 
Pitch  Diameter;  Line. — The  center  line  of  a  rolling  mill;  a  line 
parallel  with  the  axis. 


358  PITTING— POISSON'S  RATIO 

Pitting. — See  Pit;  also  page  106. 

Plain  Annealed  Wire. — See  page  508. 

Plain  Drawn  Wire. — See  page  508. 

Plain  Roll. — See  page  404. 

Plaited  Structure. — See  page  126. 

Plane. — (i)  Of  shear:  see  page  337;  (2)  of  symmetry:  see  page  123; 
(3)  of  weakness:  see  page  123. 

Planished  Sheet. — See  page  431. 

Planishing  Rolls. — See  page  415. 

Plastic. — See  page  331. 

Plastic  Compression. — See  page  63. 

Plastic  Deformation.— See  pages  279  and  281. 

Plastic  Elongation.— See  page  472. 

Plastic  Material. — See  page  331. 

Plastic  Origin. — Produced  in  a  plastic  condition. 

Plastic  Static  Deformation.— See  page  281. 

Plastic  Strain.— See  page  334. 

Plastic  Sulphur.— See  Sulphur. 

Plasticity.— See  page  331. 

Plate.— A  flat  piece  of  metal  produced  by  rolling  (rarely  by  ham- 
mering), usually  over  No.  12  gage  or  }/%"  thick;  if  thinner  than 
this  it  is  generally  called  a  sheet,  except  in  the  case  of  tin  plate. 
Plates  for  safes,  armor  plate,  etc.,  are  sometimes  made  by  welding 
together  several  plates  of  wrought  iron  or  soft  steel  and  high 
carbon  or  alloy  steel,  alternately,  which,  according  to  the  number 
employed,  are  called  three-ply,  five-ply,  etc.  See  also  page  430. 

Plate  Iron;  Metal.— See  page  383. 

Plate  Mill.— See  page  413. 

Plate  Molding. — See  page  300. 

Plated  Bars.— See  page  71. 

Platen.— See  page  301. 

Platines  (obs.). — An  old  name  given  to  the  material  rolled  into 

sheet  iron  thinner  than  boiler  plate. 
Plating. — Metallic  coating  for  protection:  see  page  370. 
Plating  Forge ;  Hammer. — See  Hammer. 
Platinite. — See  page  451. 

Platinum  Resistance  Pyrometer. — See  page  208. 
Platinum  Steels. — See  page  453. 
Platt  Process. — See  page  369. 
Plessite. — See  page  291. 
Plow  Steel  Wire.— See  page  509. 
Plug. — Of  a  converter:  see  page  17. 
Plumbago  Blacking.— See  page  298. 
Plumbago  Crucible. — See  page  in. 
Plus  Gage.— See  page  186. 
Ply.— See  Plate. 

Pneumatic  Molding  Machine. — See  page  301. 
Pneumatic  Process  (obs.). — Bessemer  processs:  see  page  15. 
Poisoning  (rare). — Of  metal,  when  some  substance  (usually  intro- 
duced in  the  process  of  manufacture)  injures  the  quality. 
Poikilitic  Structure. — See  page  125. 
Poisson's  Ratio.— See  page  336. 


POLING— POT  MELTING  359 

Poling. — Stirring  molten  metal,  either  in  a  furnace  or  in  a  ladle, 
with  a  pole  of  green  wood,  the  heat  distilling  off  the  volatile 
products  which  stir  up  the  metal  and,  together  with  the  char- 
coal formed,  help  to  reduce  any  oxides  present. 

Polish-Attack ;  Polish -Etching.— See  page  288. 

Polishing. — See  page  285. 

Polyatomic. — See  page  87. 

Polybasic. — See  page  87. 

Polycellular  Structure. — See  page  126. 

Polycentric  Structure. — See  page  126. 

Polyhedral  Steel. — See  page  443. 

Polymerism. — See  page  85. 

Polymorphic  Transformation. — See  page  327. 

Polymorphism;  -ous. — See  page  121. 

Polysomatic. — See  page  292. 

Polysynthetic  Twinning. — See  page  1 24. 

Pommarede  Method. — See  Iron. 

Pond  Sludge. — See  page  33. 

Pbnsard  Furnace ;  Process. — See  page  144. 

Pontelec  Method.— See  page  503. 

Pony  Roughing  Stand. — See  page  4*5- 

Pool  (rare). — The  hearth  of  a  reverberatory  or  other  furnace. 

Poole  Process. — See  page  73. 

Poor  Lime. — See  Flux. 

Pop  Mark  (Eng.).— See  page  473- 

Porcelanic  Fracture. — See  page  178. 

Porous.— See  page  55. 

Poryphyritic  Structure. — See  page  125. 

Port. — In  a  furnace  (generally  of  the  regenerative  type),  the  open- 
ings through  which  the  air  and  gas  enter,  and  the  products  of 
combustion  leave;  the  space  over  the  hearth. 

Porter ;  Porter  Bar. — A  long  bar  for  handling  heavy  pieces  of  metal, 
particularly  for  forging.  It  has  a  chuck  at  one  end  which  fits 
over,  or  is  welded  to,  one  end  of  the  piece,  and  a  counterweight 
at  the  other  end,  and  the  whole  is  raised  by  a  chain  fastened  at  the 
proper  point  to  balance. 

Porter  Process. — See  page  371. 

Portevin's  Method. — For  etching:  see  page  287. 

Posnikoff  Process. — See  page  60. 

Post-Eutectic.— See  page  269. 

Post-Eutectoid. — See  page  271. 

Post-Genital  Malleableness. — Not  malleable  as  produced,  but 
made  so  subsequently. 

Post-Neutral  Period. — In  solidification:  see  page  54. 

Pot. — (i)  A  box  used  in  annealing;  (2)  the  box  or  chamber  used 
in  the  cementation  process;  (3)  a  crucible;  (4)  a  ladle  (obs.). 

Pot  Annealing.— See  page  232. 

Pot  Furnace. — Crucible  Furnace. 

Pot  Galvanizing. — See  pages  370  and  431. 

Pot  Hole.— See  page  114. 

Pot  House. — See  page  112. 

Pot  Melting.— See  page  113. 


360  POT  METAL— PRESS 

Pot  Metal.— See  page  118. 

Pot  Packer.— See  page  114. 

Potash. — (i)  The  element  potassium,  e.g.,  caustic  potash  (potassium 
hydrate),  etc.;  (2)  potassium  carbonate. 

Potash  Hardening.— See  page  69. 

Potassa. — Potash. 

Potassium. — K.;  at.  wt.,  39;  melt,  pt,  62.9°  C.  (145.2°  F.); 
sp.  gr.,  0.86.  It  is  always  found  in  the  combined  state  with 
oxygen,  etc.  As  the  oxide  or  the  carbonate  it  finds  a  very 
limited  application  as  a  flux,  but  practically  never  in  the  met- 
allurgy of  iron  or  steel,  except  accidentally. 

Potential  Brittleness.— See  Brittleness. 

Potential  Recrystallization.— See  page  216. 

Potentiometer  Method. — For  temperature  measurements:  see 
page  208. 

Pottering  Down  (Eng.). — See  page  114. 

Pottery  Mine. — See  page  244. 

Pottkoff  Process. — See  page  371. 

Pouillet's  Color  Scale. — Of  temperatures:  see  page  210. 

Pouillet  Pyrometers. — (i)  Gas:  see  page  207;  (2)  pyrhelio meter: 
see  page  207. 

Pound  Calorie. — See  page  200. 

Pound-Centigrade  Heat  Unit. — See  page  200. 

Pouring. — See  pages  53  and  57. 

Pouring  Basin;  Gate. — See  page  299. 

Pouring,  Special  Methods  of. — See  page  59. 

Power. — Of  a  microscope:  see  page  285. 

Power  Gas. — See  Producer. 

Practical  Proof  Strain.— See  page  468. 

Precipitate ;  Precipitation.— See  page  88. 

Precipitation  Process.— Of  C.  W.  Siemens:  see  page  146. 

Preliminary  Slag.— See  Slag. 

Preliminary  Test. — See  Furnace  Test. 

Pre-Neutral  Period. — In  solidification:  see  page  54. 

Preparation  of  Specimens. — For  metallographic  examination:  see 
page  285. 

Prepared  Iron. — See  page  364. 

Preservative  Coatings ;  Process. — See  page  362. 

Press. — Or  hydraulic  press;  a  machine  used  for  working  metal, 
much  in  the  same  way  (except  for  special  purposes)  as  with  a 
hammer,  but  as  its  effect  penetrates  throughout  the  piece, 
its  action  being  comparatively  slow  so  that  opportunity  is 
given  for  the  metal  to  flow,  it  is  available  for  larger  pieces, 
and  also,  as  a  rule,  gives  a  much  better  sructure.  It  consists 
essentially  of  a  hydraulic  cylinder  in  which  a  plunger  or  ram 
moves  vertically  and  which  is  forced  down  upon  the  piece  of 
metal  suitably  supported  on  an  anvil  block  as  in  the  case  of 
hammers,  The  action  of  the  ram  may  be  continuous  (con- 
tinuous acting  press),  i.e.,  the  squeeze  may  be  of  the  same 
intensity  throughout  its  duration,  or  it  may  be  intermittent 
or  pulsating  (intermittent  acting  press),  increasing  and  decreasing 
while  the  actual  squeeze  is  taking  place. 


PRESS  HARDENING— PRICKING 


361 


Press  Hardening. — See  page  229. 

Presser. — That  portion  of  a  molding  machine  which  imparts  the 

necessary  pressure  to  the  molding  sand  (Homer). 
Pressing. — See  Forging. 
Pressing-in  Method. — For  determining  hardness:  see  page  477. 


FIG.  49. — 10,000  ton  hydraulic  press. 

Pressure  Hardening.— See  page  229. 
Prevost's  Law. — See  page  200. 
Price  and  Nicholson  Process. — See  page  118. 
Prick-punch  Marks.— See  page  473. 
Pricking. — In  wire  drawing:  see  page  508. 


362  PRIMARY  AUSTENITE— PRODUCER 

Primary  Austenite. — See  page  274. 

Primary  Cementite. — See  page  273. 

Primary  Crystals. — See  page  121. 

Primary  Crystallization. — See  page  1 20. 

Primary  Furnace. — See  page  316. 

Primary  Gas. — See  page  33. 

Primary  Hardening. — See  page  447. 

Primary  Metals. — See  Secondary  Metals. 

Primary  Slip. — See  page  283. 

Primary  Stress. — See  page  332. 

Primaustenal,  Primaustenoid. — See  page  275. 

Primes. — Of  sheets:  see  page  433. 

Priming  Coat. — See  page  365. 

Primitive  Elastic  Limit. — See  page  471. 

Prince  Process. — See  page  387. 

Principal  Stress. — See  page  332. 

Prinsep  Method. — For  temperature  measurements:  see  page  209. 

Print. — See  page  285. 

Printing  Methods  of  Etching. — See  page  288. 

Prismatic  Cleavage. — See  page  1 24. 

Prismatic  Structure. — See  page  125. 

Prismatic  Sulphur. — See  Sulphur. 

Prismatic  System. — Of  crystallization:  see  page  120. 

Process  Annealing. — See  page  509. 

Process  Metallurgy. — See  Physical  Metallurgy. 

Producer ;  Producer  Gas. — Rarely  called  generator  gas;  this  is  a 
fuel  gas  produced  by  blowing  air  through  a  thick  bed  of  incan- 
descent carbon  (generally  coal),  the  theoretical  reaction  giving  a 
composition  by  volume  of  23%  of  carbon  monoxide  and  77%  of 
nitrogen.  As  ordinarily  made,  a  certain  amount  of  steam  is 
blown  in  with  the  air,  the  proportion  being  such  that  the  tem- 
perature of  the  bed  of  fuel  is  not  unduly  lowered.  The  advan- 
tage from  the  use  of  steam  consists  in  preventing  the  excessive 
formation  of  clinkers  by  keeping  the  temperature  from  becom- 
ing too  high,  and  also  by  converting  the  extra  specific  heat 
into  latent  heat  in  the  reaction  between  the  steam  and  the 
carbon,  this  heat  being  recovered  later  when  the  gas  is  burned. 
The  gas  made  with  steam  is  sometimes  called  mixed  gas,  being 
a  combination  of  straight  producer  gas  and  water  gas,  and  the 
process,  mixed  process;  it  is  also  known  as  semi-water  gas, 
Dowson  gas  (Eng.),  or  power  gas.  The  composition  by  volume 
of  a  good  grade  of  gas  from  a  modern  producer  using  bituminous 
coal  and  steam  is  about: 

Carbon  monoxide 26  % 

Hydrogen 13 

Hydrocarbons 4 

Carbon  dioxide 4 

Nitrogen 53 

The  apparatus  in  which  the  gas  is  made  is  called  a  gas  pro- 
ducer or  simply  a  producer,  rarely  a  gas  generating  furnace 


PRODUCTS  OF  COMBUSTION— PROTECTION      363 

or  generator.  The  first  practical  producer  was  designed  by  C.  W. 
Siemens  (from  which  came  the  name  Siemens  gas),  and  consisted 
of  a  brick  chamber  in  which  the  fuel  was  supported  on  an  inclined 
grate,  and  air  alone  was  used.  On  account  of  the  construction, 
the  producer  had  to  be  shut  down  at  frequent  intervals  in  order 
to  clean  out  the  ashes.  A  modern  producer  consists  essentially  of , 
a  cylindrical,  fire-brick,  combustion  chamber  containing  the  bed 
of  fuel  through  which  the  air  and  steam  are  forced,  usually  from 
the  bottom,  and  under  pressure;  if  suction  is  used,  it  is  termed  a 
suction  producer.  The  resulting  gas  is  taken  off  at  the  top 
through  suitable  openings.  If  the  air  and  steam  are  forced 
through  from  the  top  to  the  bottom,  it  is  called  a  down-draft 
producer.  The  fuel  is  fed  in  at  the  top  through  a  hopper,  and  the 
ashes  are  cleaned  out  at  the  bottom  as  a  rule  through  a  water  seal 
(water  seal  producer),  the  action  practically  always  going  on 
uninterruptedly  (continuous  producer),  as  it  is  not  economical 
to  take  the  producer  out  of  service  except  when  the  gas  is  no 
longer  needed. 

Products  of  Combustion. — See  page  202. 

Product  of  Rolling  Mills. — See  page  411. 

Pro-Eutectic. — See  page  269. 

Pro-Eutectic  Austenite. — See  page  275. 

Pro-Eutectic  Cementite. — See  page  273. 

Pro-Eutectic  Ferrite. — See  page  275. 

Pro-Eutectoid. — See  page  271. 

Pro-Eutectoid  Cementite. — See  page  273. 

Pro-Eutectoid  Ferrite. — See  page  272. 

Profile  (Eng.). — The  section  or  shape  of  rolled  iron  or  steel. 

Progressive  Fracture. — See  page  179. 

Progressive  Freezing. — See  pages  54  and  266. 

Prony  Brake. — See  page  483. 

Proof  Load;  Strain;  Strength;  Weight.— See  page  468. 

Proof  Test.— See  pages  467  and  482. 

Properties  of  Crystals. — See  page  121. 

Properties  of  Materials. — See  page  330. 

Proportional  Limit. — See  page  334. 

Proportionality. — (i)  Law  of:  see  page  473;  (2)  limit  of:  see  page 
334- 

Protected  Metal.— See  Protection. 

Protection. — In  cementation:  see  page  70. 

Protection. — The  prevention  of  corrosion  (q.v.)  in  iron  or  steel, 
which,  however,  is  only  relative,  is  effected  by  means  of  pro- 
tective coatings  or  coverings  which  are  either  inert  or  very 
resistant  to  corrosion,  such  as  tar  or  concrete,  or  are  acted  upon  in 
preference  to  the  iron,  such  as  zinc,  and  are  of  three  kinds:  (a) 
those  simply  adhering  to  the  surface  of  the  object,  composed 
of  some  extraneous  substance,  e.g.,  paint;  (6)  those  formed  by 
the  oxidation  of  the  surface  (oxide  coating) ;  and  (c)  those  which 
may  be  a  combination  of  the  two  preceding,  or  where  a  metal 
coating  forms  an  alloy  where  it  comes  in  contact  with  the  object. 
Such  coatings  and  the  processes  for  producing  them  are  desig- 
nated protective,  preservative,  or  inoxidizing.  Articles  which 


364  PROTECTION 

have  a  protective  oxide  coating  are  sometimes  termed  black 
iron  objects.  In  practically  every  case  the  surface  of  the  iron 
must  be  carefully  cleaned  before  any  kind  of  coating  is  applied. 

Passivity  or  Passive  State. — If  a  piece  of  iron  (also  certain 
other  metals)  is  immersed  in  concentrated  nitric  acid,  strong 
solutions  of  chromic  acid  or  potassium  bichromate  (chromatic  pro- 
tection), or  exposure  to  certain  other  strongly  oxidizing  reagents, 
it  is  only  slightly  attacked;  and  if  subsequently  placed  in  acid  or 
other  solution  which  would  ordinarily  attack  it  vigorously,  it  still 
remains  almost  unaffected.  The  rate  of  solubility  in  dilute  nitric 
acid  is  sometimes  made  a  measure  of  the  degree  of  passivity; 
where  relatively  large  proportions  of  NO2  are  evolved  has  been 
termed  the  passive  break,  i.e.,  the  dividing  line.  Iron  in  this 
condition  has  been  termed  passive,  passivated,  passivified, 
inactive,  altered,  or  prepared,  and,  as  a  contradistinction,  when 
in  its  ordinary  condition,  fresh  iron.  This  inactivity  may  be 
removed  by  scratching  the  surface  or  touching  it  with  an  active 
substance;  also  by  making  it  the  cathode  with  the  passage  of  a 
sufficiently  powerful  current.  The  change  from  the  active  to  the 
passive  condition  is  not  necessarily  abrupt,  but  may  be  gradual, 
so  that  passivity  may  exist  in  varying  degrees  of  retardation. 

Anodic  passivity  or  polarization  is  where  the  object  forms  the 
anode  in  an  electrolyte;  non-anodic  passivity  or  polarization, 
where  the  object  is  not  part  of  an  electrolytic  couple,  also  called, 
in  contradistinction  to  the  former,  chemical  passivity.  Faraday's 
oxide  or  oxygen  theory  assumed  the  surface  to  be  oxidized;  this 
had  to  be  abandoned  when  it  was  found  that  chromium  could  be 
rendered  inactive  without  actual  oxidation.  This  was  modified 
in  the  oxide  skin  or  oxide  film  theory  on  the  assumption  that  the 
metal  was  protected  by  a  thin  covering  of  oxide.  Finkelstein's 
valency  theory  assumed  differences  in  valency  of  the  metal. 
LeBlanc's  reaction-velocity  theory  assumed  the  passage  of  the 
metal  to  be  accompanied  by  a  chemical  change;  if  this  was  slow 
the  metal  was  passive.  Fredenhagen's  oxygen  charge  or 
oxygen  film  theory  was  due  to  his  finding  that  when  an  anode  was 
polarized  the  potential  rose  gradually,  which  led  him  to  believe 
this  was  due  to  a  slow  oxidation,  an  oxygen  film  forming  over  the 
surface  of  the  electrode.  He  assumed  that  oxygen  or  oxide  was 
present  in  the  metal  as  a  solid  solution.  Foerster  and  Schmidt's 
hydrogen  or  catalysis  theory ;  that  passivity  was  the  normal  state 
for  pure  iron,  and  that  activity  was  due  to  the  presence  of  some 
catalytic  agent,  particularly  hydrogen.  In  the  peroxide  or 
adsorption  theory  it  was  assumed  that  iron  ions  were  oxidized  to  a 
high  oxide  (perhaps  FeO3)  which  were  then  adsorbed  by  the  sur- 
face of  the  metal.  Sackur's  anion  discharge  theory  is  similar 
to  LeBlanc's  and  assumes  that  the  velocity  with  which  the  metal 
is  attacked  depends  on  the  accessibility  of  the  discharged  anion. 
Reichinstein's  constant  sum  theory  states:  "The  sum  of  the 
concentrations  of  all  the  constituents  of  the  electrode  volume  is 
always  constant.  Electrode  volume  is  simply  an  hyyothesis  of 
Reichinstein's  to  account  for  the  possibility  of  the  displacement 
of  one  substance  by  another.  He  found  that  the  sum  total  of  all 


PROTECTION  365 

concentrations  at  this  surface  must  be  constant,  and  therefore 
talked  about  concentrations.  If  you  substitute  for  concentra- 
tion the  idea  of  the  extent  to  which  a  surface  is  covered  with 
atoms,  then,  instead  of  the  sum  of  the  concentrations  being 
constant,  you  say  the  total  sum  of  the  spaces  on  the  surface  is 
constant.  You  then  get  Reichinstein's  hypothesis  in  different 
language,  so  you  can  then  talk  about  electrode  volume  as  the 
electrode  surface."  (The  above  is  largely  based  on  The  Passive 
State  by  Bennett  and  Burnham,  /.  Am.  Electrochem.  Soc., 
XXIX,  1916). 

Where  corrosion  is  due  to  electrolysis,  methods  have  been 
devised  or  suggested  consisting  in  setting  up  a  counter  e.m.f.  of 
greater  intensity.  This  is  the  principle  of  the  Cumberland 
process  where  the  shell  of  the  boiler  forms  the  cathode,  and  the 
anodes  are  pieces  of  iron  suspended  in  the  water  and  insulated 
from  the  shell.  A  continuous  current  at  a  low  voltage  is  em- 
ployed and  successful  results  are  claimed;  it  is  also  said  to  be  effect- 
ive in  removing  scale  and  in  preventing  its  formation.  Pieces 
(protectors)  of  zinc,  which  is  electro-positive  to  iron,  connected 
with  the  shell,  have  also  been  tried,  but  such  practice  has  received 
only  a  limited  application. 

Paint,  from  a  commercial  viewpoint,  is  a  substance  applied  in 
liquid  form  to  produce  a  protective  coating.  It  is  composed  of 
(i)  a  solid  substance  in  a  fine  state  of  division,  known  as  the 
pigment  or  coloring  matter,  and  the  base  or  principal  constituent 
(these  may  be  the  same),  and  (2)  the  vehicle  or  menstruum  in 
which  they  are  held  in  suspension.  The  pigment  or  base  may  be 
a  metal  or  a  chemical  compound.  Where  the  vehicle  is  linseed 
oil,  a  drier  consisting  of  a  salt  of  manganese  or  some  other  sub- 
stance is  often  added  to  hasten  the  oxidation  (hardening)  of  the 
oil.  The  body  of  a  paint  is  its  covering  power,  i.e.,  the  relative 
amount  of  surface  a  given  quantity  will  cover  thoroughly.  When 
more  than  one  coat  is  applied  the  first  is  called  the  priming  coat ; 
when  applied  to  structural  material  shipped  ready  for  erection  it  is 
termed  a  shop  coat  or  field  coat.  A  coating  employed  for  pipes, 
known  as  Angus  Smith's  solution,  originally  consisted  of  coal  tar, 
tallow,  slaked  lime,  fine  rosin,  and  coal  naptha;  as  used  at  present 
the  mixture  generally  consists  of  coal  tar  and  pitch  oil  in  the 
proportion  of  about  two  to  one,  and  it  is  heated  nearly  to  the  boil- 
ing point  when  the  pipes,  cleaned  from  scale  and  rust,  are  dipped 
in  it.  Collodion  is  occasionally  employed  for  coating  objects, 
but  the  film  is  thick,  which  is  disadvantageous  for  certain  pur- 
poses, and  also  is  easily  destroyed. 

Lacquer  is  a  varnish  made  by  dissolving  shellac  in  wood 
alcohol  with  the  addition  of  other  substances,  particularly 
some  pigment.  Japan  is  similar  to  a  varnish  made  by  dis- 
solving shellac  in  hot  linseed  oil  to  which  a  drier,  such  as  litharge, 
is  usually  added.  Black  Japan  or  Japan  lacquer  is  asphaltum 
dissolved  in  linseed  oil  and  thinned  with  turpentine. 

Caustic  soda  (NaOH)  or  caustic  potash  (KOH),  in  strong 
solutions,  has  a  marked  effect  in  preventing  rust,  and  for  this 
reason  cleaned  articles  are  frequently  dipped  in  a  concentrated 


366  PROTECTION 

solution  of  one  of  these  salts.  So-called  boiler  compounds  are 
sometimes  used  to  neutralize  free  inorganic  or  organic  acids 
which  may  be  present,  and  for  this  purpose  usually  contain  some 
powerful  base  such  as  sodium  carbonate.  One  such  compound 
contains  sodium  carbonate,  tri-sodium  phosphate,  dextrine,  and 
a  substance  with  tannin.  The  use  of  lime  direct  is  objectionable 
owing  to  the  scale  which  is  likely  to  result,  and  its  employment  is 
generally  restricted  to  preliminary  purification  of  water  in  large 
tanks,  which  also  results  in  softening  the  water  and  so  reducing 
scale  for  the  removal  of  which,  when  formed,  special  compounds 
are  advocated. 

Influence  on  Corrosion  of  Certain  Elements. — A  few  years  ago 
the  theory  was  advanced  that,  if  iron  could  be  manufactured 
approximately  pure,  that  is,  free  from  the  usual  metalloids  and 
impurities,  it  would  show  extreme  resistance  to  corrosion.  Later 
work,  however,  indicates  that  several  of  the  metalloids,  within 
certain  limits,  are  rather  beneficial  than  harmful  in  their  effects  on 
the  corrosion  rate. 

Carbon. — Under  0.20%,  carbon  has  little  influence  on  corro- 
sion. From  0.20  to  the  eutectoid  (0.85)  percent,  there  is  a  gradual 
increase  in  the  corrosion  rate  with  additional  carbon,  and  from 
the  eutectoid  percent  up  to  approximately  1.25%  the  curve 
again  drops. 

Manganese. — A  belief  that  manganese  increases  corrosion  is 
still  held  by  some  metallurgists.  Recent  work,  however,  seems 
to  prove  that  the  real  offender  is  sulphur  (see  Sulphur  below), 
and  not  manganese,  and  that  the  latter,  instead  of  increasing, 
slightly  lowers  the  corrosion  rate. 

Sulphur. — The  corrosion  rate  increases  directly  with  the  sul- 
phur content,  and  corrosion  is  especially  rapid  in  steels  and 
irons  approximately  free  from  copper  and  carrying  an  abnormally 
high  amount  of  sulphur. 

Phosphorus. — Phosphorus  has  little  or  no  influence  on  the 

corrosion  rate.     It  has  been  noticed  that,  when  a  comparatively 

small  amount  of  phosphorus  is  added  to  steel,  the  corrosion  is 

\  slightly  less,  which  is  probably  due  to  the  deoxidizing  effect  of 

added  phosphorus. 

Silicon. — In  the  amounts  normally  present  in  open  hearth 
and  Bessemer  steel,  this  element  has  no  effect  on  corrosion. 
If  as  much  as  9.10%  or  more,  however,  is  added,  the  corrosion 
rate  is  increased. 

Copper. — Copper  has  a  remarkable  influence  in  lowering  the 
corrosion  rate  of  steel  or  iron,  even  when  present  in  very  small 
quantities.  It  has  the  effect  of  neutralizing  the  influence  of 
sulphur,  and  the  rust  film  on  the  surface  of  the  steel  gradually 
becomes  protective  rather  than  accelerative  as  is  the  case  with 
steels  and  irons  comparatively  free  from  copper. 

Nickel. — The  influence  of  nickel  is  similar  to  that  of  copper, 
except  that  probably  more  nickel  than  copper  is  required  to 
produce  a  similar  increased  resistance. 

Cobalt. — It  is  quite  probable  that  cobalt  in  the  lower  ranges 
slightly  decreases  the  corrosion  rate.  When  cobalt  is  alloyed 


PROTECTION  367 

with  steel  to  the  amount  of  approximately  12%,  together  with 
a  little  chromium,  a  product  is  obtained  which  is  practically 
unacted  upon  by  any  corrosive  agent. 

Chromium. — Chromium  tends  to  reduce  corrosion  especially 
in  amounts  over  about  6%.  What  is  known  as  stainless  steel 
contains  about  10  to  15%. 

Oxide  Coatings. — Rust,  produced  by  slow  oxidation  and 
well  known  by  its  brownish,  yellowish  or  reddish  color,  consists 
principally  or  wholly  of  ferric  oxide  (Fe2Oa),  hence  readily  parts 
with  a  portion  of  its  oxygen  to  the  metal  beneath,  absorbing 
a  fresh  supply  from  the  surrounding  atmosphere  or  other  medium, 
thus  setting  up  a  catalytic  cycle  of  which  it  is  the  agent.  The 
oxide  or  scale  which  rapidly  forms  on  iron  objects  when  they  are 
heated  to  high  temperatures  consists  almost  entirely  of  the 
magnetic  oxide  (FesO-i);  while  it  does  not  so  readily  part  with 
oxygen,  it  is  only  slightly  adherent  when  produced  in  this  way 
and,  being  easily  detached,  offers  little  protection.  Hence  the 
necessity  for  special  treatment  to  yield  an  adherent,  non-corrosive 
coating  (rust  proof  coating).  One  of  the  simplest  methods  is 
known  as  blueing  which  is  effected  by  heating  an  object  until 
the  previously  cleaned  surface  takes  on  a  thin  oxide  film  of  that 
color.  It  is.  so  thin  that  it  is  quickly  worn  off  when  handled, 
and  accordingly  its  protection  is  relatively  slight.  Barff's 
process  consists  in  passing  superheated  steam  over  the  objects 
which  are  heated  in  a  muffle  to  about  500°  F.  (260°  C.);  for  more 
complete  protection  a  temperature  of  1200°  F.  (650°  C.)  is  em- 
ployed. Such  objects  are  said  to  be  barffed.  "  George  Bower 
interested  himself  in  this  process  and  tried  using  air  instead  of 
steam  (Bower  process);  he  was  not  successful,  however,  until 
his  eldest  son,  A.  S.  Bower,  conceived  the  idea  of  using  a  pro- 
ducer gas  rich  in  carbonic  oxide  to  reduce  the  red  oxide,  as 
obtained  by  air  treatment,  either  by  barffing,  or  by  subjecting 

the  work  to  acid  fumes The  air  treatment  lasted  40 

minutes  and  the  gas  treatment  20  minutes,  these  being  repeated 
alternately  four  or  eight  times.  Finally  the  Barff  patents  were 
purchased  in  order  to  secure  a  satisfactory  first  coating  of  red 
oxide  in  a  practical  manner.  The  combined  process,  known  as 
the  Bower-Barff  process,  consisted  in  heating  the  articles  to  be 
coated  in  a  closed  retort  to  a  temperature  of  1600°  F.  (871°  C.); 
superheated  steam  was  then  injected,  forming  a  coating  of  both 
magnetic  oxide  (Fe3O4)  and  red  oxide  (Fe/)3);  this  first  operation 
lasted  20  minutes,  and  was  followed  by  the  injection,  during 
15  to  25  minutes,  of  carbonic  oxide  (CO)  from  a  gas  producer 
which  reduced  the  FeaOs  to  Fe3O4.  These  operations  could  be 
repeated  alternately  any  number  of  times  until  a  sufficient 
depth  of  oxide  had  been  obtained"  (Alfred  Sang,  /.  T.  R., 
September  16,  1909).  , 

The  Swan  process  is  a  patented  modification  of  the  Bower- 
Barff  process.  The  articles  to  be  treated  are  first  placed  in  a 
muffle  furnace  with  the  following  substances,  preferably  as 
follows:  Copper  sulphate,  30  parts;  sal  ammoniac,  i  part;  tannin, 
2  parts;  and  glucose,'  3  parts.  They  are  heated  to  about  1050° 


368  PROTECTION 

F.  (620°  C.),  and  superheated  steam  is  injected  for  about  30 
minutes.  They  are  taken  from  the  furnace,  permitted  to  cool, 
and  then  submerged  in  paraffin  oil  heated  to  about  150°  F. 
(65°  C.).  They  are  then  dried  in  air  and  have  a  dead-black, 
coating.  Repeated  treatments  are  not  necessary  unless  a 
heavier  coating  is  required.  In  Bertrand's  process  the  iron  to  be 
coated  is  first  carefully  cleaned  by  immersion  in  dilute  sul- 
phuric acid  (5%),  and  preferably  brushed.  It  is  then  rubbed 
with  grain  or  sand  until  quite  clean,  and  immersed  for  four  or 
five  seconds  in  a  bath  consisting  of  200  grams  of  acid  tin  salts, 
600  grams  of  sulphate  of  copper,  and  300  grams  of  sulphovinic 
acid  in  100  liters  of  water.  The  work  should  then  have  a 
yellowish  bronze  color;  it  is  washed  in  water  containing  ;Hj% 
of  oxalic  acid,  dried  and  heated  in  an  oven  the  atmosphere  of 
which  may  be  either  oxidizing  or  reducing.  The  time  required 
varies  somewhat  according  to  the  temperature  employed;  but 
about  10  minutes  is  stated  to  give  a  fairly  adherent  coating  of 
magnetic  oxide  which  is  capable  of  resisting  atmospheric  in- 
fluences very  perfectly  (Turner).  Bontempi's  process  con- 
sists in  heating  iron  objects  to  approximately  1000°  F.  (540°  C.) 
in  a  closed  and  preferably  air-tight  chamber,  the  iron  having 
been  previously  treated  according  to  the  Bower-Barff  process 
or  not,  as  desired,  when  it  is  subjected  to  the  gas  or  vapor  of 
one  or  more  non-corrodible  substances.  When  the  Bower- 
Barff  process  is  omitted,  the  temperature  need  be  only  high 
enough  to  insure  volatilization  of  the  non-corrodible  substance. 
Browning  is  used  largely  for  gun  barrels.  The  method  in  use 
at  the  Woolwich  Arsenal  (Journ.  I.  6*  S.  /.,  1881)  is  as  follows: 
The  barrels,  etc.,  are  first  scalded  in  a  solution  of  soda  for  20 
minutes,  and  are  then  washed  in  clean  water.  The  brown- 
ing mixture  is  applied  and  they  are  exposed  to  a  damp  heat 
for  about  i  %  hours,  when  they  are  scalded  again  and,  when  cool, 
the  rust  is  scratched  off.  This  process  is  repeated  four  times 
and  then  the  barrels  are  cleaned  off  and  oiled.  The  whole 
operation  takes  about  8  hours.  The  browning  mixture  consists  of : 

Spirits  of  wine 5  oz. 

Spirits  of  niter 8  " 

Tincture  of  steel  (chloride  of  iron) 8  " 

Nitric  acid 4  " 

Sulphuric  acid 3  " 

Blue  vitriol. 4  " 

Water i  gal. 

Sometimes  browned  steel  is  produced  by  simply  rubbing  the 
surface  with  a  mixture  of  zinc  chloride  and  olive  oil.  The 
Buffingtpn  process,  used  for  parts  of  guns,  etc.,  consists  in 
suspending  the  objects  for  five  minutes  or  more  in  pure  molten 
niter,  containing  manganese  dioxide,  at  a  temperature  where 
sawdust  thrown  on  the  surface  will  burn;  the  pieces  are  then 
hung  for  a  few  minutes  over  the  pot  and  afterward  placed  in 
boiling  water  to  remove  any  niter  adhering  to  the  surface;  this 
method  produces  a  fine  bronze  color.  Claudius'  process 


PROTECTION  369 

consists  in  dipping  the  articles  in  a  5  to  6%  solution  of  man- 
ganese nitrate  and  drying  them  slowly  over  a  fire,  the  opera- 
tion being  repeated  until  a  coating  of  the  desired  thickness  is 
obtained;  any  loose  powder  is  brushed  off  after  each  operation. 
In  Forbes'  process  the  articles  are  heated  in  a  mixture  of  man- 
ganese dioxide  or  some  similar  substance  mixed  with  a  neutral 
material.  In  Gesner's  process  the  articles  are  heated  in  gas- 
fired  retorts  for  about  20  minutes  at  a  temperature  of  1000° 
to  1200°  F.  (540°  to  650°  C.),  when  superheated  steam  is  in- 
troduced for  about  35  minutes.  After  this  a  small  quantity 
of  naphtha  is  run  in  and  the  heating  continued  for  10  minutes; 
steam  is  again  admitted  for  15  minutes.  The  De  Wees  Wood 
process  was  earlier  than,  and  practically  identical  with,  the 
preceding  and  was  applied  to  sheets.  The  hydraesfer  process 
(patented  by  Bradley)  is  somewhat  similar  to  the  Bower-Barff 
process  and  requires  but  one  furnace  operation  which  lasts  one 
hour  or  less;  the  color  of  the  coating  is  a  blue  black.  The 
process  owes  its  name  to  the  use  of  brass  in  connection  with 
the  partly  decomposed  steam  which  is  injected  into  the  retort. 
The  metal  to  be  coated  is  kept  at  a  temperature  of  about  1100° 
F.  (595°  C.).  A.  de  Meritens'  process  consists  in  placing 
the  object  in  water  at  a  temperature  of  70°  to  80°  C.  (160°  to 
175°  F.)  where  it  constitutes  the  anode  of  an  electrolytic  cell. 
An  electric  current,  just  strong  enough  to  decompose  the  water, 
is  used  and  the  oxygen  liberated  forms  a  thin  black  layer  of 
magnetic  oxide  which  withstands  rubbing  and  may  be  pol- 
ished. No  previous  cleaning  is  necessary.  If  the  current  is 
too  strong  the  oxide  will  not  be  adherent;  it  is  also  found  ad- 
vantageous to  have  hydrogen  present  in  the  iron  by  first  passing 
the  current,  for  a  short  time,  in  the  opposite  direction. 

The  Parker  rust  proof  process  consists  in  immersing  the 
pieces  to  be  treated  in  a  bath  containing  about  2  %  of  a  mixture 
of  phosphoric  acid,  manganese  dioxide,  etc.,  heated  to  about 
the  boiling  point.  The  pieces,  previously  cleaned,  are  allowed 
to  remain  in  the  bath  a  variable  length  of  time,  depending  upon 
their  composition,  or  until  effervescence  ceases.  They  are  then 
removed  and  dipped  in  oil.  The  surface  produced  has  the 
appearance  of  gun  metal.  C.  Platt's  method,  intended  for  wire, 
consists  in  exposing  it  to  the  action  of  steam  containing  acid  vapor 
which  produces  a  fine  brown  coating  in  a  few  hours.  It  is  then 
heated  for  an  hour  at  a  temperature  of  100°  to  125°  C.  (210°  to 
255°  F.),  dipped  in  oil,  the  superfluous  oil  removed  in  a  cen- 
trifugal machine,  and  the  wire  again  heated. 

Spellerizing  is  a  process,  devised  especially  for  treating  the 
metal  for  steel  tubes,  consisting  in  first  subjecting  the  skelp  at 
the  proper  temperature  to  the  action  of  rolls  having  regularly 
shaped  projections  on  their  working  surfaces,  and  other  rolls 
with  smooth  surfaces,  the  object  being  to  knead  and  work  the 
surface  of  the  skelp  (roll-knobbling)  to  produce  a  more  adherent 
scale  and  one  better  adapted  to  resist  corrosion,  especially  in  the 
form  of  pitting.  In  G.  Weigelin's  process  the  objects  are  heated 
in  a  furnace  so  arranged  that  they  may  be  exposed  alternately 
24 


370  PROTECTION 

to  reducing  and  oxidizing  gases,  whereby  a  film  of  magnetic  oxide 
is  produced. 

Enameling  is  a  method  of  producing  a  smooth,  opaque,  vitre- 
ous coating  (glaze  or  enamel)  on  metals.  The  enamel  is  usually 
put  on  as  a  powder  or  solution  of  which  silica  is  practically 
always  a  constituent;  this  is  baked  or  fused.  It  may  be  applied 
in  one  coat,  or  sometimes  a  non-vitreous  material,  called  the 
base  material,  is  first  applied  and  heated  or  burned  in  to 
make  it  adherent,  after  which  the  top  coat  or  glaze  is  fused  on. 
One  method  of  producing  a  silicate  coating  on  pipes  is  to  cover 
the  cores  (in  the  mold)  with  a  mixture  of  silicates  of  lime  and 
magnesia  which  are  fused  when  the  molten  metal  comes  in 
contact  with  them  and  become  firmly  attached  to  the  surface. 
Dode's  inoxidizing  process  consists  in  depositing  successive 
layers  of  lead  or  silicate  on  iron  and  steel,  and  then  gilding,  platin- 
izing, or  bronzing  them.  The  Hydrogen  Company's  process 
is  used  for  soil  pipes,  and  requires  about  two  hours.  The 
pipes  are  heated  in  retorts  to  the  desired  temperature,  and 
steam  is  admitted  for  about  one  hour.  Some  hydrocarbon 
liquid  is  then  injected  with  steam  into  the  retort.  The  coating 
produced  is  claimed  to  unite  with  the  iron  and  not  form  a  mere 
paint.  Ward's  inoxidizing  process  is  for  producing  a  dull  black 
coating  on  objects  of  cast  iron  or  steel  by  dipping  them  in  or 
painting  them  with  a  solution  of  some  silicate.  After  dipping, 
the  articles  are  heated  in  a  furnace  at  a  temperature  which  causes 
the  silicate  partially  to  fuse  and  to  unite  with  the  iron. 

Metallic  Coatings. — Various  methods  may  be  employed  for 
applying  the  metal,  such  as  dipping  in  a  molten  bath,  depositing 
electrolytically,  applying  in  a  finely  divided  form,  as  a  paint,  by 
welding,  and  heating  in  contact  with  the  powdered  metal  (metallic 
cementation).  Galvanizing  (rarely  termed  zinc  plating)  is 
a  process  for  coating  metal  with  a  thin  layer  of  zinc.  It  is 
so  called  from  the  fact  that  a  galvanic  couple  is  formed,  of 
which  the  zinc  is  the  more  electro-positive,  and  hence,  when 
exposed  to  corrosive  action,  is  dissolved  in  preference  to  the 
iron,  etc.  Before  the  coating  is  applied,  the  surface  of  the 
object  is  cleaned  from  scale  and  dirt  by  pickling  or  some  other 
means.  According  to  the  usual  method,  termed  pot  galvaniz- 
ing or  hot  galvanizing,  the  object  is  dipped  in  molten  zinc  or 
spelter  (commercial  zinc)  contained  in  an  iron  vessel  or  pot. 
at  a  temperature  usually  about  810°  to  840°  F.  (430°  to  450°  C.). 
The  surface  of  the  molten  zinc  is  largely  protected  from  oxi- 
dation by  a  layer  of  ammonium  chloride.  In  Winiwarter's 
process,  intended  more  especially  for  sheets-,  the  tank  is  kept 
nearly  full  of  lead  (to  prevent  the  formation  of  hard  zinc),  on 
top  of  which  is  a  layer  of  zinc  about  an  inch  thick  containing 
2  or  3%  of  tin  to  promote  crystallization.  Before  coating, 
the  sheets  are  cleaned  Aby  dipping  in  a  dilute  solution  of 
chlorides  of  zinc  and  ammonium.  In  Kuffler's  process 
superfluous  zinc  is  removed  from  the  surface  of  sheets  by  means 
of  wire  brushes.  Bedson's  continuous  process  is  that  very 
generally  adopted  for  galvanizing  wire  (see  page  509).  Reese's 


PROTECTION  371 

process  is  also  a  modification  adapted  for  wire,  in  which  the 
wire  is  galvanized  in  bundles  without  uncoiling,  and  then  put 
immediately  inside  the  drum  of  a  centrifugal  machine  by  means 
of  which  the  excess  of  zinc  is  thrown  to  the  periphery.  Porter's 
process  is  devised  for  removing  the  excess  of  zinc  from  articles 
by  placing  them  while  still  hot  in  a  vibrating  hopper,  the  surplus 
zinc  collecting  at  the  bottom,  while  the  articles  themselves 
are  delivered  before  reaching  the  bottom.  Electro-galvanizing, 
also  called  cold  galvanizing,  is  where  the  object  to  be  coated 
with  zinc  is  attached  (af ter^  cleaning)  to  the  negative  electrode 
(kathode)  in  an  electrolytic  bath,  metallic  zinc  constituting 
the  anode,  and  a  soluble  salt  of  zinc  the  electrolyte.  In  the 
Cowper-Cowles  process  the  electrolyte  is  zinc  sulphate,  which 
is  regenerated  by  circulating  it  through  tanks  containing  zinc 
dust.  In  S.  Wagner's  process  the  zinc  anode  is  covered  with 
flannel  saturated  with  a  solution  of  zinc  and  is  moved  over  the 
surface  of  the  object.  Electrolytic  methods  of  galvanizing, 
which  differ  slightly  in  details  from  those  described,  have  been 
devised  by  Heathfield,  H.  Paweck,  Pottkoff,  Rawson,  and 
Walker.  Sherardizing  is  a  process  of  dry  galvanizing  invented 
by  Sherard  Cowper-Cowles.  The  articles,  after  cleaning,  are 
placed  in  a  retort,  usually  a  revolving  drum,  with  zinc  dust, 
commonly  called  blue  powder.  This  is  the  flue  dust  produced 
in  the  manufacture  of  zinc,  and  contains  about  75  to  90%  of 
pure  zinc.  A  small  amount  of  powdered  charcoal  is  added  to 
prevent  oxidation  of  the  zinc  from  the  air  inside  the  retort  at 
the  beginning  of  the  operation,  and  the  receptacle  is  closed  and 
heated  to  a  temperature  about  200°  F.  (110°  C.)  below  the  melt- 
ing point  of  zinc.  The  zinc  appears  to  form  a  true  alloy  with  the 
iron.  This  method  is  used  principally  for  objects  such  as  bolts 
and  small  castings,  and  does  not  appear  to  be  applicable  to 
sheets.  After  exposure,  this  coating  assumes  a  grayish-blue 
appearance,  which  does  not  interfere  with  its  resisting  properties, 
called  the  curing  color. 

Coatings  of  tin,  or  a  mixture  of  tin  and  lead,  are  used  prin- 
cipally for  thin  plates  or  sheets,  known  respectively  as  tin 
plates  and  terne  plates,  which  are  described  under  Sheets  and 
Tin  Plate.  Nickel  plating  and  copper  plating  are  usually  done 
by  electrolytic  methods,  the  object  to  be  coated  forming  the 
kathode,  a  piece  of  the  metal  for  the  coating,  the  anode,  and  a 
solution  of  some  salt  of  the  same  metal,  the  electrolyte.  In  nickel 
plating,  a  preliminary  coating  of  copper  is  often  applied  to  make 
the  nickel  more  adherent.  Copper  may  also  be  deposited  from 
solution  by  a  purely  chemical  reaction  with  metallic  iron  whereby 
a  corresponding  amount  of  the  iron  goes  into  solution. 

The  electrolytic  method  is  generally  used  where  a  relatively 
thin  coating  is  desired  on  a  finished  object;  frequently  also  as 
a  preparation  for  nickel  or  other  additional  plating  owing  to  the 
better  adherence  thus  secured.  This  method  may  also  be  carried 
further  to  secure  a  thicker  layer  where  the  coated  steel  in  the 
form  of  billets  is  subsequently  rolled  or  worked  down  as  in 
the  production  of  small  sections  such  as  rods  and  wire.  In  this 


372  PROTECTION 

second  case  the  same  object  may  be  attained  by  a  welding  process 
by  first  depositing  a  relatively  thin  coating  and  then  inserting 
the  piece  in  a  closely  fitting  tube  of  copper,  the  whole  being  sub-- 
sequently  heated  to  a  moderate  rolling  temperature  and  squeezed 
into  intimate  contact,  usually  in  a  rolling  mill.  The  product  is 
referred  to  as  copper  clad  steel.  Of  a  similar  nature  is  the 
Monnot  process.  Here  the  copper  is  cast  around  a  piece  of  steel 
and  the  compound  billet  then  rolled  and  drawn  down,  etc.,  or 
the  heated  billet  may  first  be  dipped  in  a  bath  of  copper  at  a 
high  temperature  (to  produce  a  copper-iron  alloy  film)  and  then 
into  a  second  bath  at  a  much  lower  temperature  where  the 
necessary  thickness  of  coating  is  secured.  By  the  electrolytic 
or  welding  methods  the  junction  of  the  two  metals  depends 
only  upon  the  very  intimate  contact,  which  is  claimed  to  be 
better  for  use  as  electrical  conductors  then  where  the  junction  is 
formed  by  an  actual  alloy.  The  Willis'  process  is  somewhat 
similar  but  varies  in  certain  details.  The  term  coppered  steel 
is  generally  understood  to  refer  to  a  copper  coating,  but  is  oc- 
casionally applied  to  steel  containing,  as  one  of  its  ingredients,  a 
small  percentage  of  that  metal,  the  preferable  term  being, 
however,  copper  steel  (see  page  453).  In  this  connection  W.  H. 
Walker  suggested  the  term  ferro-brass  to  illustrate  the  simi- 
larity of  the  reduced  corrosion  of  copper  steel  to  that  of  zinc  to 
which  copper  has  been  added  (forming  brass). 

Coatings  of  aluminum  may  be  applied  as  in  hot  galvanizing, 
or  as  a  paint  the  base  of  which  is  finely  ground  aluminum.  A 
number  of  special  methods  have  been  devised.  Calorizing 
is  a  process  for  the  protection  of  metals  against  oxidation  at 
high  temperatures.  The  coating,  called  insuluminum,  is  claimed 
to  prevent  indefinitely  oxidation  below  1000°  C.  (1830°  F.)  and 
to  increase  the  life  greatly  at  higher  temperatures.  It  consists 
in  heating  the  pieces  to  be  treated  in  a  mixture  of  powdered 
aluminum,  alumina%  and  about  i%  of  sal  ammoniac  in  a 
gas-tight  receptacle  filled  with  a  reducing  or  inert  gas;  the  heating 
is  slow  and  the  time  is  usually  two  or  three  hours,  depending  upon 
conditions  and  the  results  to  be  obtained.  Its  principal  ap- 
plication is  for  furnace  parts,  pyrometer  tubes,  combustion 
tubes,  etc.  (W.  E.  Ruder).  The  percentage  of  aluminum 
varies  from  about  5  to  50%  by  weight.  For  copper  and  brass 
objects  the  mixture  is  kept  low  in  aluminum  and  the  heating  is 
carried  out  at  about  700°  to  800°  C.  (1290°  to  1470°  F.).  For 
steel  and  iron  objects,  richer  mixtures  are  employed  and  the 
temperature  is  increased  to  900°  to  950°  C.  (1650°  to  1740°  F.). 
These  mixtures  may  be  used  repeatedly  with  the  addition  of 
the  amount  of  aluminum  and  ammonium  chloride  necessary  to 
make  up  the  loss.  The  Van  Aller  process  is  very  similar,  the 
metallic  objects  to  be  coated  being  heated  in  revolving  drums 
with  mixtures  containing  finely  divided  aluminum.  Alumaloyd 
is  the  trade  name  for  sheets  coated  with  aluminum  by  a  special 
process.  It  is  claimed  that  such  sheets  can  be  worked  without 
cracking  the  coating,  and  that  the  surface  is  particularly  adapted 
for  painting  where  a  high  finish  is  desired. 


PROTECTION  373 

The  spraying  of  metals  from  the  molten  state  is  an  old  idea 
for  producing  powders,  and  the  spraying  of  a  liquid  to  produce 
a  covering  of  paint,  varnish  or  enamel  is  also  well  known.  It 
has  recently  been  adapted  to  produce  uniform  metallic  deposits. 
In  the  Schoop  process  a  metallic  powder  is  driven  at  high 
velocity  against  the  surface  of  the  body  to  be  coated,  by  means 
of  gaseous  jets  expanded  from  considerable  pressure.  In  earlier 
attempts  the  metal  was  melted  in  a  pot,  forced  under  high  pres- 
sure through  a  fine  nozzle,  and  sprayed  on  the  surface  with 
steam  or  gas.  Morf  devised  a  machine  to  combine  pulveriza- 
tion and  deposition.  The  essential  parts  of  this  machine  or 
pistol  are  a  combined  melting  and  spraying  jet  and  a  feed  mechan- 
ism. The  metal  to  be  used,  in  the  form  of  a  rod  or  wire,  is  fed 
to  the  melting  flame  which  can  be  gas,  acetylene,  hydrogen, 
etc.,  in  air  or  oxygen.  For  the  best  cohesion  the  surface  must 
be  thoroughly  cleaned,  preferably  by  a  sand  blast.  Schoop's 
new  method  is  based  on  the  conception  that  the  force  with 
which  the  solid  molecules  are  driven  against  the  surface  brings 
them  into  the  liquid,  or  at  least  the  malleable,  state,  resulting 
in  perfect  union  and  the  consequent  formation  of  a  homogeneous 
body  (Morcom,  /.  Inst.  Met.,  1914,  II).  A  modification  in- 
troduced by  C.  F.  Jenkins  is  based  on  the  action  of  an  electrical 
fuse  which  deposits  and  blows  a  shower  of  very  minute  metallic 
particles  on  the  surface.  The  Lohmann  or  Lohmannizing 
process  is  used  for  coating  iron  and  steel  sheets  with  a  pro- 
tective alloy  which  is  claimed  to  extend  below  the  surface  and 
to  fill  every  pore  or  cavity.  It  appears  to.  depend  upon  the  use 
of  what  is  called  the  Lohmann  bath  containing  an  "amalga- 
mating" salt  and,  later,  an  immersion  in  a  molten  alloy.  The 
metal  is  pickled  and  then  dipped  in  this  bath  where  a  metallic 
salt  is  deposited,  and  the  sheets  are  then  dried  and  immersed 
in  a  molten  alloy  which  is  kept  at  a  temperature  of  950°  to  1000° 
F.  (510°  to  540°  C.).  When  the  submerged  objects  have  reached 
a  temperature  of  about  500°  F.  (260°  C.)  the  previously  deposited 
salt  is  driven  off  and  leaves  the  surface  in  a  perfectly  clean  con- 
dition where  it  is  replaced  by  the  coating  metal.  An  important 
feature  of  the  process  is  the  use  of  an  alloy  of  zinc,  lead  and  tin, 
the  proportions  of  which  are  varied  to  suit  requirements. 
Kalamein  is  the  trade  name  for  a  coating  of  lead,  tin  and  anti- 
mony applied  in  a  manner  similar  to  hot  galvanizing.  It  is 
used  especially  for  tubes  and  similar  objects  (said  to  be  kala- 
meined).  It  is  of  a  silvery  color,  resembling  the  appearance  of 
galvanized  objects,  but  without  spangles,  and  is  not  cracked  or 
injured  by  bending  or  rough  handling. 

Miscellaneous  methods. — A.  Bucher  recommends  applying 
the  following  solution: 

Distilled  water i%  pints 

Tartaric  acid 50  grains 

Stannous  chloride 150     ' 

Mercuric  chloride 30 .  • " 

Indigo  solution 750    " 


374  PROTECTIVE  COATINGS— PUDDLING 

diluted  with  100  times  its  volume  of  water.  A.  M.  Villon's 
process  consists  in  subjecting  the  object  to  the  vapor  of  sulphur, 
which  combines  with  the  iron  forming  a  sulphide  coating. 

Protective  Coatings;  Process. — See  page  363. 

Protector. — See  page  365. 

Proving.— See  page  467. 

Proximate  Analysis. — See  page  82. 

Proximate  Structural  Composition. — See  page  337. 

Pseudocrystalline  Structure. — See  page  125. 

Pseudosymmetry. — See  page  125. 

Pseudomorph;  Pseudomorphic  Crystal. — See  page  122. 

Puddle  Ball.— See  page  376. 

Puddle  (Puddled)  Bar.— See  page  377. 

Puddle  Cinder.— See  page  377. 

Puddle  (Puddled)  Iron. — Wrought  iron  made  by  the  puddling 
process. 

Puddle  (Puddled)  Steel. — Iron  made  by  the  puddling  process 
which  contains  enough  carbon  to  be  hardened  by  quenching: 
see  page  379. 

Puddle  Train. — See  page  413. 

Puddlers'  Candles. — See  page  376. 

Puddlers'  Mine  (Eng.).-— See  page  376. 

Puddling,  Puddling  Process. — This  process  has  for  its  object 
the  production  of  wrought  or  malleable  iron  (rarely  steel)  by 
oxidizing  and  removing  most  of  the  silicon,  carbon,  manganese, 
and  phosphorus  contained  in  pig  iron,  the  operation  being 
conducted  on  the-  hearth  of  a  reverberatory  furnace.  The 
charge  during  the  early  stages  is  molten,  but,  owing  to  the 
temperature  not  being  sufficiently  high,  the  final  product  is 
in  a  pasty  state,  and  for  this  reason  is  mechanically  mixed 
with  a  certain  proportion  of  slag,  most  (but  never  all)  of  which  is 
removed  during  subsequent  steps  in  its  manufacture. 

Until  1784  all  wrought  or  malleable  iron  was  made  by  some 
direct  process  (q.  v.)  or  by  similar  means.  In  this  year,  however, 
Henry  Cort  patented  the  process  of  puddling  (hence  Cort's 
process)  by  which  it  is  produced  from  pig  iron  in  a  reverberatory 
or  air  furnace,  without  the  assistance  of  an  air  blast.  The 
furnace  at  first  was  lined  with  sand,  which  combined  with 
the  iron  which  was  oxidized,  and  caused  a  very  heavy  loss; 
there  was  little  if  any  removal  of  phosphorus,  and  the  operation 
was  slow.  This  method  is  called  dry  puddling  (on  account 
of  the  relatively  small  amount  of  slag)  to  distinguish  it  from 
the  later  method  (at  present  used  exclusively)  where  the  furnace 
is  lined  with  some  form  of  iron  oxide,  called  wet  puddling  or 
simply  puddling,  and  iron  oxide  is  also  charged  to  form  a  slag. 
Formerly  puddling  meant  the  practice  employing  refined  pig, 
and  boiling  or  pig  boiling,  where  unrefined  pig  was  used,  but 
now  this  distinction  is  not  generally  observed,  as  the  pig  is  seldom 
refined. 

Puddling  Furnace. — The  hearth  (sometimes  called  basin  or 
puddling  basin)  is  built  of  cast-iron  plates  carried  on  brick 
walls  or  on  short  iron  pillars.  It  is  usually  about  5  or  6  feet 


PUDDLING 


375 


long,  and  4  feet  wide  opposite  the  charging  door.  Resting 
upon  and  extending  around  the  sides  of  the  hearth  is  a  box, 
or  a  double  wall,  of  cast  iron  8"  or  10"  high,  through  which 
water  circulates.  The  iron  bottom  is  also  sometimes  double 
and  water-cooled.  Air  may  be  substituted  for  water  as  a 
cooling  medium.  The  fuel  is  generally  bituminous  coal,  al- 
though gas  is  occasionally  used  (see  below  under  special  fur- 
naces). For  coal  the  grate  has  an  area  of  about  6  square  feet, 
sometimes  10  or  more.  The  grate  bars  are  separately  detach- 
able to  allow  of  cleaning  any  part  of  the  fire,  and  also  so  they 
may  be  replaced  when  necessary.  Between  the  grate  and  the 
hearth  is  a  fire-brick  wall  (bridge  wall)  extending  from  side 
to  side  and  rising  sufficiently  high  to  prevent  any  of  the  fuel 
from  passing  over  on  the  hearth,  or  any  metal  or  slag  from 
falling  on  the  fuel.  The  hearth  at  the  other  end,  next  the 


PIG.  50. — 500-lb.  puddling  furnace. — (Stoughton,  Met.  of  I.  andS.) 


chimney,  terminates  in  a  second  bridge  (altar)  which  prevents 
the  overflow  of  the  metal  at  that  end.  Beyond  this  the  fur- 
nace flue  inclines  downward  and  terminates  at  the  chimney 
flue.  At  the  foot  of  this  there  may  be  an  opening  (floss  hole) 
through  which  any  cinder  overflowing  the  altar  may  escape,  and 
warmed  by  a  fire  to  keep  this  cinder  (flue  cinder)  molten.  On 
the  side  of  the  furnace  opposite  the  middle  of  the  hearth  is 
the  working  door.  This  is  about  20"  square  and  is  closed 
by  a  slide  lined  with  fire-brick  which  can  be  raised  or  lowered. 
A  small  opening  (rabbling  hole)  at  the  bottom  of  the  door  large 
enough  to  admit  a  rabble  permits  the  workman  to  stir  the 
charge,  protected  from  the  heat,  and  also  without  admitting  a 
large  amount  of  cold  air.  The  roof  of  the  furnace  is  an  arch 
about  2  feet  high  at  the  fireplace  and  sloping  gradually  until,  at 
the  chimney,  it  is  less  than  a  foot  above  the  bottom  of  the  flue. 

I 


376  PUDDLING 

The  furnace  just  described  is  known  as  a  single  furnace  and  has  a 
capacity  of  about  400  to  600  pounds  and  is  the  type  generally 
employed.  If  two  such  furnaces  are  placed  back  to  back  with 
the  separating  wall  omitted,  it  is  called  a  double  furnace,  and 
can  take  a  charge  over  twice  as  great  as  a  single  furnace.  Two 
double  furnaces  placed  side  by  side,  with  the  separating  wall 
omitted,  constitute  a  double-double  furnace  or  a  quadruple 
furnace. 

Lining  and  Fettling. — The  bottom  and  sides  of  the  hearth 
are  covered  with  ore  or  slag  rich  in  iron  oxide,  etc.,  which  is 
set  by  heating  to  a  high  temperature.  After  the  preceding 
charge  has  been  drawn,  the  hearth  is  repaired  (fettled  or  fixed) 
by  throwing  in  up  to,  say,  200  pounds  of  ore,  etc.,  slightly  mois- 
tened. The  material  for  this  purpose  is  called  fettling  or  some- 
times (Eng.)  fix,  mill  fix,  or  puddlers'  mine.  Bull  dog  (Eng.) 
is  calcined  tap  cinder.  Best  tap  (Eng.)  is  a  specially  prepared 
puddling  cinder,  consisting  principally  of  magnetic  and  ferric 
oxides.  The  slag  in  the  furnace  from  the  previous  heat  is 
commonly  allowed  to  remain.  If  the  lining  becomes  eaten 
away,  exposing  the  cast-iron  plates,  the  furnace  is  said  to  have 
a  cold  bottom. 

Operation. — After  fettling,  about  200  to  600  pounds  of  pig  iron 
are  thrown  in,  and  the  door  closed.  In  about  20  minutes 
they  (and  some  of  the  oxides)  begin  to  melt,  and  when  fusion 
is  complete  the  bath  is  worked  with  a  rabble  (an  iron  tool 
resembling  a  hoe)  to  expose  the  iron  to  the  action  of '  the  slag 
and  the  flame.  The  silicon  is  'oxidized  first,  and  when  this 
has  nearly  all  disappeared  the  iron  clears,  i.e.,  loses  the  mottled 
appearance  it  formerly  had.  The  phosphorus  is  also  eliminated 
during  this  and  the  later  period.  The  temperature  is  now 
slightly  lowered  and  the  carbon  is  attacked,  the  resulting  evolu- 
tion of  carbon  monoxide  constituting  the  period  known  as 
the  boil  (rarely  called  sibbering  or  stewing).  This  gas  burns 
in  little  pale-blue  jets  of  flame,  called  puddlers'  candles,  and 
during  its  escape  puffs  up  the  cinder  so  that  the  level  of  the 
bath  is  raised  (high  boil).  Corresponding  to  the  loss  of  carbon 
the  charge  becomes  more  and  more  pasty,  and  the  bath  drops 
to  its  former  level  (drop  of  the  bath) ,  and  about  this  time  grains 
of  nearly  pure  iron  appear  on  the  surface  and  the  iron  is  said 
to  have  come  to  nature  or  to  have  been  brought  to  nature; 
this  condition  is  sometimes  termed  drying,  and  the  iron  is 
called  ready  iron  or  young  iron.  At  this  point  the  charge  must 
be  well  worked  up  to  insure  proper  welding  together  of  the 
particles.  When  the  action  is  complete  the  pasty  mass  is 
broken  up  with  a  bar  into  lumps  called  balls  or  puddle  balls 
(the  operation  is  termed  balling)  of  about  100  to  200  pounds  each, 
which  are  drawn  successively  with  tongs  and  taken  to  be 
squeezed,  an  operation  to  expel  most  of  the  slag,  and  also  to 
weld  the  grains  of  iron  together.  The  total  time  of  the  charge 
is  about  i  to  i%  hours. 

If,  after  charging,  the  pigs  are  not  moved  about,  part  of  the 
iron  may  melt  at  too  high  a  temperature  (hot  melting)  and 

\ 


PUDDLING  377 

stick  to  the  bottom  (aproning)  in  an  insufficiently  decarburized 
condition.  If  the  removal  of  carbon  is  too  rapid  the  grains 
of  iron  are  coarse  and  form  a  compact  mass  difficult  to  work 
and  ball  (gobbed  heat).  Rodney  (Eng.)  is  cold  cinder  sticking 
to  a  piece  of  old  iron  put  into  the  furnace  to  help  bring  on  the 
boil.  A  cobble  is  a  ball  which  has  been  drawn  too  soon  and 
must  consequently  be  put  back  in  the  furnace. 

In  some  cases  part  of  the  cinder  may  be  removed  just  before 
the  boil  and  is  called  boilings,  the  remainder,  if  removed  at 
the  end  of  the  process,  is  known  as  tappings  or  puddle  (puddling) 
cinder.  A  furnace  is  said  to  have  a  dry  bottom  when  the  slag 
is  drawn  off  at  intervals  (this  operation  is  termed  bleeding); 
a  wet  bottom  is  where  the  slag  is  allowed  to  remain.  The  fluid, 
vitreous  cinder  on  top  of  the  bath  is  occasionally  called  floss. 

Squeezing. — The  machine  for  this  operation  is  termed  a 
squeezer,  and  may  be  of  several  types.  The  present  form, 
known  as  a  rotary  squeezer, 
coffee  mill  squeezer,  or  Burden 
squeezer,  consists  of  a  cylinder 
with  teeth,  like  a  cog  wheel, 
mounted  on  a  vertical  shaft  and 
revolving  inside  a  casing  set  ec- 
centrically, the  ball  being  inser- 
ted at  the  point  where  the  dis- 
tance between  them  is  greatest, 
and  the  slag  expelled  while  it  is 
carried  around  to  the  point  where 
the  distance  is  smallest.  On  the 
same  principle  a  cam  may  be 
mounted  on  either  a  horizontal  T?T_ 
or  a  vertical  shaft  and  revolve  *£•  Si.-Burden  squeezer 
inside  a  suitable  casing  (cam  "(Thurston,  Iron  and  Steel.) 
squeezer).  Winslow's  squeezer  has  a  cam  revolving  in  a 
vertical  plane.  Head's  squeezer  consists  of  three  rolls,  pro- 
vided with  grooves  and  collars,  arranged  much  like  a  set  of  plate 
bending  rolls.  In  Siemens'  squeezer,  three  horizontal  rams 
opposed  to  each  other,  operated  by  hydraulic  power  or  by  steam, 
squeeze  the  ball  on  a  turntable.  The  original  type  of  machine, 
called  an  alligator  squeezer  or  crocodile  squeezer,  consisted 
of  an  anvil  block,  upon  which  the  ball  was  laid,  and  a  vibrating 
toothed  jaw  which  alternately  pressed  down  upon  the  ball 
and  rose  to  allow  of  changing  its  position.  The  use  of  hammers 
was  still  older,  and  the  operation  was  termed  shingling  (rarely 
nobbing). 

Piling. — After  squeezing,  the  rough  bloom  is  rolled  into  a 
flat  bar  known  as  muck  bar  or  puddle  (puddled)  bar.  This  is 
cut  up  into  short  lengths  (if  broken,  the  operation  is  known  as 
cabbling)  and  a  number  piled  together,  termed  a  pile,  to  be 
reheated  in  a  furnace,  called  a  reheating  furnace,  balling  furnace 
(Eng.),  or  mill  furnace,  and  rerolled,  when  more  of  the  slag  is 
expelled.  Ordinarily  the  pieces  of  muck  bar  are  all  laid  the  same 
way,  but  occasionally  the  bars  in  alternate  layers  are  placed 


378 


PUDDLING 


crosswise,  and  this  arrangement  is  called  cross  piling  Instead, 
of  piles  a  rough  box  may  be  made  up,  the  sides,  bottom,  and  top 
consisting  of  pieces  of  muck  bar,  the  interior  of  which  is  filled 
with  miscellaneous  small  iron  scrap;  this  is  termed  a  fagot 
(faggot),  or  box  piling,  and  the  operation,  fagoting;  the  iron  so 
produced  is  sometimes  called  fagoted  iron. 

Product. — The  material,  in  general,  is  called  puddled  iron, 
and  after  rerolling  is  known  as  refined  iron,  refined  bar,  mer- 
chant bar,  single  rolled  iron,  single  refined  iron,  or  No.  2  iron ; 
if  subjected  to  a  second  piling,  heating,  and  rerolling,  double 
(doubly)  refined  iron,  double  rolled  iron,  No.  3  iron,  best  bar, 
wire  iron,  or  also  refined  bar.  Horseshoe  iron  is  a  superior 
grade  made  by  piling  and  rerolling  old  iron  horseshoes.  Two 
obsolete  products  are  stampings  and  lumps  which  are  (Percy) 
rough  plates  about  12"  square,  the  former  being  about  i%" 
thick,  and  the  latter  4"  to  5"  thick. 


FIG.  52. — Alligator  squeezer. — (Thurston,  Iron  and  Steel.) 

Theories  of  Puddling. — The  oxidation  of  the  impurities 
is  due  to  the  oxide  of  iron  present,  rather  than  to  the  direct 
action  of  the  oxygen  in  the  air.  Siemens  considered  that 
magnetic  oxide,  Fe3O4,  was  the  active  agent  (magnetic  oxide 
theory)  which  is  generally  accepted,  while  Snelus  referred  the 
action  to  ferric  oxide,  Fe2O*  (ferric  oxide  theory). 

The  action  will  probably  be  most  readily  understood  by  con- 
sidering a  piece  of  cast  (pig)  iron  heated  in  contact  with  the  air. 
A  crust  or  shell  of  oxide  is  formed,  and,  upon  removing  this,  the 
metallic  iron  which  is  left  will  be  found  to  contain  practically 
the  same  percentage  of  impurities  as  originally.  This  oxidizing 
action  may  be  continued,  and  the  metallic  iron  which  remains 
will  have  the  same  composition  even  if  the  temperature  is  suffi- 
cient to  cause  the  scale  to  melt,  provided  this  is  allowed  to  drain 
off.  As  soon,  however,  as  the  melted  scale  or  slag  remains  in 
contact  with  the  iron,  particularly  if  the  iron  is  molten,  a  new 
state  of  affairs  is  found  to  exist.  The  magnetic  oxide,  FesO-i, 
of  which  the  scale  is  principally  composed,  readily  parts  with  one 
atom  of  its  oxygen  which  combines  with  the  carbon,  silicon,  etc., 
of  the  iron,  and  is  itself  reduced  to  ferrous  oxide,  FeO,  thus: 


C  +  Fe304  = 
Si  +  2Fe3O4 


CO  +  3FeO 
=  SiO2  +  6FeO 


PUDDLING  379 

Most  of  the  ferrous  oxide  is  reoxidized  by  the  air  to  magnetic 
oxide  which  again  reacts  with  the  impurities,  and  this  cycle 
goes  on  indefinitely;  a  small  portion,  however,  is  reduced  to 
metallic  iron  which  is  dissolved  by  the  bath: 

FeO  +  C  =  Fe  +  CO 
The  phosphorus  and  manganese  are  similarly  oxidized,    thus: 

2P  +  sFe304  =  P205  +  i5FeO 
also 

Mn  +  Fe203  =  MnO  +  2FeO 

Scrap  Iron. — Instead  of  starting  the  process  with  pig  iron, 
as  described,  scrap  iron  may  be  employed.  This  is  generally 
of  small  size,  called  busheling  scrap  from  the  fact  that  it  can 
be  gathered  up  in  a  bushel  basket,  and  is  heated  in  a  furnace 
(busheling  furnace  or  scrap  furnace)  the  same  as  a  regular 
puddling  furnace.  The  charge  is  usually  the  right  amount  to 
form  one  ball  (scrap  ball),  which  is  handled  in  the  same  way  as 
a  puddle  ball.  The  material,  after  squeezing,  and  the  first 
rolling,  is  called  scrap  bar  or  bushel  (-ed)  bar;  the  final  product, 
busheled  iron.  A  swarfing  furnace  is  the  same  as  a  busheling 
furnace,  but  the  scrap  used  is  much  finer.  Large  pieces  of  scrap 
are  heated  and  welded  or  rolled  direct,  or  made  up  into  fagots  as 
described  above.  Common  iron  is  wrought  iron  made  from  coke 
pig;  finer  grades  are  made  from  charcoal  pig  (charcoal  iron). 

Puddled  (puddle)  steel  is  made  in  very  much  the  same  way 
as  puddled  iron,  and  the  same  cinder  may  be  used,  but  the 
process  is  arrested  before  there  is  such  a  complete  removal  of 
carbon,  and  must  be  conducted  at  a  lower  temperature.  The 
product  contains  roughly  up  to  about  0.5%  of  carbon  (wrought 
iron,  usually  under  0.1%),  but  there  is  no  sharply  drawn  line 
between  the  two:  the  steel  must  be  capable  of  hardening. 

The  working  of  the  charge  is  now  practically  always  carried 
on  by  hand:  mechanical  devices  have  been  tried  from  time  to 
time,  but  have  achieved  only  a  temporary  consideration. 
Mechanical  rabble,  mechanical  stirrer,  or  rarely  (Eng.)  iron 
man,  is  a  machine  which  worlH  the  charge  in  an  ordinary  (or 
special)  type  of  furnace.  The  furnace,  or  simply  the  hearth, 
may  be  rotated  in  a  vertical  or  a  horizontal  plane  to  effect  the 
same  thing:  such  a  furnace  is  called  a  rotary  puddling  furnace, 
rotator,  mechanical  puddler,  puddling  machine,  or  rotating 
puddling  machine.  Modifications  of  these,  as  well  as  of  ordi- 
nary furnaces,  consist  principally  of  the  application  of  various 
mechanical  devices  which  need  not  be  mentioned. 

Barnett's  process  consisted  in  applying  a  solution  of  salt 
to  the  lining  of  the  furnace  to  improve  it. 

Beasley's  process  consists  in  using  a  mixture  of  powdered 
puddling  cinder  and  blue  billy,  treated  with  hydrochloric  acid, 
to  which  lime  and  salt  are  afterward  added.  This  is  painted 
on  the  surface  of  the  lining,  after  fettling,  and  is  claimed  to 
remove  a  greater  amount  of  phosphorus,  and  also  to  increase 
the  output. 


380  PUDDLING 

According  to  W.  W.  Collins*  process  pig  iron  was  melted  in 
the  ordinary  way  with  a  large  quantity  of  silicate  of  iron  or 
other  metallic  oxide.  The  melted  mass  was  allowed  to  remain 
quietly  until  the  iron  began  to  rise,  when  it  was  vigorously 
worked  at  a  high  temperature  and  balled.  The  product  was 
to  be  melted  in  crucibles  with  the  addition  of  the  desired  amount 
of  carbon. 

E.  A.  Cowper's  process  consists  in  blowing  preheated  air 
and  combustible  gas  on  the  bath. 

Hewitt's  process  consisted  in  granulating  the  pig  and  mixing 
it  with  oxide  of  iron,  the  melting  and  working  being  conducted 
as  usual. 

Hunt's  process  consisted  in  working  metal,  partly  decar- 
burized  in  a  Bessemer  converter,  in  a  puddling  furnace  or  a 
charcoal  hearth. 

In  Jones  and  Jones'  process  partial  purification  of  the  pig 
was  performed  in  the  ordinary  way,  the  final  treatment  and 
balling  being  conducted  in  a  rotary  furnace. 

In  W.  Middleton  and  P.  Hayward's  furnace  between  the 
ordinary  puddling  furnace  and  the  chimney  is  a  retort,  heated 
by  the  waste  gases,  in  which  the  pig  iron,  before  being  intro- 
duced into  the  furnace,  is  melted  and  purified  with  a  blast  of 
air. 

The  Pietzke  process  employs  a  special  furnace  which  is 
gas  fired  and  is  connected  directly  with  a  gas  producer.  It 
has  two  hearths  which  can  be  rotated  jointly  180°.  The  charge 
is  introduced  into  the  hearth  which  is  farthest  from  the  fire, 
and  the  operation  is  completed  by  rotating  it  to  the  position 
nearest  to  the  fire,  two  charges  being  worked  at  the  same  time. 

In  Riepe's  process  (for  steel)  about  280  pounds  of  pig  were 
melted  and  cinder  was  added.  It  was  then  puddled  with  the 
addition  of  a  little  black  oxide  of  manganese,  common  salt,  and 
dry  clay  previously  ground  and  mixed.  When  this  had  acted  for 
a  few  minutes,  40  pounds  of  heated  pig  were  put  in,  and  boiling 
.commenced.  When  grains  began  to  form,  they  were  worked 
under.  He  claimed  that  the  most  important  part  of  the  process 
was  the  regulation  of  the  temperature  during  the  final  operation. 

Sherman's  process  consisted  in  adding  potassium  iodide 
to  the  metal  under  treatment. 

W.  Spielfield,  to  prevent  oxidation  of  puddled  or  raw  steel, 
heated  the  lumps  or  balls  in  retorts  or  closed  vessels. 

Taylor's  process  was  to  cool  the  puddle  balls,  without  squeez- 
ing, then  crush  them  and  Separate  the  small  refined  particles 
from  the  coarse  unrefined  ones.  The  former  were  heated  and 
balled;  the  latter  retreated. 

E.  Bonehill  used  direct  metal  with  mixers.  Guenyveau 
suggested  a  steam  and  air  jet;  Guest  and  Nasmyth,  a  steam 
jet;  Trick,  Davis,  Daniel  and  Phillips  also  suggested  steam. 

J.  J.  Osborne's  process  consisted  in  adding  a.  physic  com- 
posed of  various  proportions  of  salt,  burnt  lime,  and  hammer 
slag.  Ostlund  proposed,  in  the  case  of  refractory  Swedish 
pig,  to  refine  in  a  revolving  iron  pot,  lying  in  an  inclined  posi- 


PUDDLING  BASIN— PURIFICATION  PROCESSES      381 

tion,  and  heated  with  carbonic  oxide  introduced  through  a 
blowpipe.  In  Sterling's  process  about  half  a  per  cent  of  tin 
was  added  to  the  charge,  but  this  made  the  iron  difficult  to 
forge  and  weld. 

Puddling  Basin. — See  page  374. 

Puddling  Cinder. — See  page  377. 

Puddling  Furnace. — See  page  374- 

Puddling  Machine. — See  page  379. 

Puddling  Mine  (Eng.). — Roasted  hematite,  suitable  for  use  in 
puddling  furnaces. 

Puddling  Operation ;  Process. — See  page  376. 

Puddling  Product. — See  page  378. 

Puddling,  Theories  of.— See  page  378. 

Puffed. — Of  rolls:  see  page  430. 

Pull  Over  Mill.— See  page  408. 

Puller  Out. — See  page  115. 

Pulling. — Of  castings:  see  page  56. 

Pulling  Test.— See  page  469. 

Pulpit. — An  elevated  platform  commanding  a  view  of  the  entire 
mill,  where  the  various  appliances  are  situated  for  controlling  its 
operation. 

Pulverize. — To  reduce  to  powder  or  a  fine  state  of  division  by 
crushing  or  grinding. 

Punch. — A  machine  or  tool  for  making  holes  in  metal  by  forcing  out 
a  certain  portion. 

Punching. — Producing  a  hole  in  a  body  by  driving  a  blunt-nosed 
instrument  through  it,  the  displaced  material  being  almost 
entirely  removed  from  and  forced  out  at  the  farther  side,  only  a 
very  small  proportion  being  forced  into  the  wall  (distinction  from 
piercing) ;  see  also  Cold  Working  and  Forging. 

Punching  Test. — See  page  477. 

Punish. — To  subject  material  to  very  severe  or  abusive  treatment. 

Pure. — Of  materials,  free  from  impurities  or  undesirable  elements, 
or  where  these  are  so  low  they  do  not  exert  a  harmful  influence; 
degrees  of  chemical  purity:  see  page  89. 

Pure  Cast  Iron;  White  Iron. — Pig  iron  nearly  free  from  everything 
but  carbon. 

Pure  Chemistry. — See  page  81. 

Pure  Flexure.— See  page  332. 

Pure  Stress;  Normal  Stress;  Internal  Normal  Stress;  Shearing 
Stress. — See  page  332. 

Purification. — (i)  Of  metals:  see  Purification  Processes,  also  page 
56;  (2)  of  water:  see  page  366. 

Purification  Processes. — Those  which  are  concerned  (a)  prin- 
cipally wi  h  the  removal  from  pig  iron  of  silicon,  phosphorus, 
and  sulphur,  the  action  being  stopped  when  the  carbon  is  at- 
tacked, the  product  being  further  treated  in  some  other  process; 
and  (7>)  embracing  certain  details  or  modifications  applied  to  ordi- 
nary processes  for  making  iron  or  steel.  From  a  practical  stand- 
point the  term  is  not  considered  to  include  the  regular  processes  for 
the  manufacture  of  wrought  iron  and  steel,  although  from  strictly 
theoretical  considerations  they  would  also  be  included. 


382 


PURIFICATION  PROCESSES 


Oxidation  is  the  general  means  employed,  the  metal  treated 
being  nearly  always  in  a  molten  condition.  Decarburization 
(decarbonization),  desulphurization,  dephosphorizatipn,  and 
desiliconization  are  the  technical  terms  used  respectively  for 
the  removal  of  carbon,  sulphur,  phosphorus,  and  silicon.  The 
general  principle  to  be  observed  is  that  at  a  low  temperature, 
with  oxidizing  conditions,  and  in  the  presence  of  a  basic  slag 


FIG.  53.— Melting  finery.— (Stoughton,  Met.  of  I.  &•  S.) 

(basic  purifying  processes),  phosphorus  and  silicon  are  oxi- 
dized in  preference  to  carbon.  If  the  slag  is  not  basic  then 
the  phosphorus  will  not  be  removed.  Under  oxidizing  con- 
ditions the  removal  of  sulphur  is  uncertain.  Under  strongly 
reducing  conditions,  and  with  a  basic  slag,  as  in  the  blast  furnace, 


PURIFICATION  PROCESSES  383 

the  removal  of  sulphur  is  under  fairly  good  control,  the  action 
being  due  to  the  formation  of  sulphides  of  calcium  and  manganese 
which  pass  into  the  slag. 

The  terms  commonly  employed  for  this  special  treatment 
are  fining,  refining,  hearth  refining,  refinery  process,  or  refin- 
ing process,  and  the  furnace  employed  is  called  a  finery,  finery 
fire,  refinery,  refinery  hearth,  refining  hearth,  running-out 
fire,  and  run-out  fire.  These  embrace  the  earliest  method 
employed  which  is  still  used  to  a  limited  extent.  The  appara- 
tus consists  df  a  hearth,  generally  rectangular,  built  up  of  naked, 
water-cooled,  iron  plates,  blast  being  usually  supplied  by  two 
tuyeres  opposite  to  each  other,  and  with  a  capacity  of  about 
^  to  2  tons  of  pig.  The  fuel  is  either  coke  or  charcoal  (coke  finery 
or  refinery;  charcoal  finery  or  refinery),  and  the  pig  is  charged 
either  molten  or,  more  commonly,  solid.  The  fuel  is  burned  by 
the  blast  from  the  tuyeres,  which  also  supplies  the  necessary 
oxygen  for  oxidizing  the  silicon,  etc.  If  ore  is  added  part  of  the 
phosphorus  is  removed.  Each  charge  takes  about  two  hours, 
less  if  the  metal  is  initially  molten.  The  product  (fine  metal, 
finer's  metal,  refined  metal,  metal,  or  refined  cast  iron)  is  tapped 
out  on  the  iron  plates  of  the  floor  (plate  metal)  or  into  iron  molds. 
It  has  a  white  fracture  (white  metal)  due  to  the  absence  of  silicon. 
It  is  sometimes  tapped  directly  into  the  furnace  in  which  the  final 
treatment  is  to  take  place  and  the  furnace  is  then  termed  a  melt- 
ing finery  or  refinery.  The  loss  of  iron  is  about  5  to  20%,  and  the 
fuel  required,  about  J^  to  %  of  the  weight  of  the  metal  charged. 
Parry  tried  to  hasten  the  process  by  blowing  a  jet  of  air  and 
superheated  steam  on  the  bath  of  pig  in  a  refinery,  which  modi- 
fication he  called  a  steam  refinery.  A  melting  down  refinery 
is  one  in  "which-  selected  pig  and  scrap  are  employed,  instead 
of  pig  alone.  The  product  of  charcoal  fineries  or  charcoal 
hearths  is  frequently  known  as  charcoal  hearth  cast  iron,  and 
the  process  is  sometimes  called  frischen  process,  from  the 
German,  whence  the  name  German  forge  sometimes  applied. 
Where  the  process  is  carried  further,  and  wrought  iron  is  produced, 
will  be  found  discussed  under  Charcoal  Hearth  Processes. 

Pig  washing  processes  are  a  modification  of  ordinary  refining. 
They  consist  in  treating  molten  pig  iron  with  molten  oxides 
(oxides  of  iron,  occasionally  mixed  with  oxides  of  manganese) 
in  a  reverberatory  furnace.  At  the  low  temperature  employed, 
and  in  the  presence  of  the  very  basic  slag,  most  of  the  silicon 
and  the  phosphorus  are  removed,  the  metal  being  tapped  out 
before  the  carbon  has  been  materially  attacked.  The  elimi- 
nation of  the  silicon  and  the  phosphorus  may  amount  to  90 
or  95%.  In  Bell's  pig  washing  process  (Bell's  dephosphoriz- 
ing process)  the  molten  pig  is  agitated  with  molten  oxides  of 
iron;  Krupp's  pig  washing  process  (patented  a  couple  of  months 
later)  is  essentially  the  same,  except  that  a  certain  proportion 
of  oxide  of  manganese  was  used  and  the  operation  was  usually 
carried  out  in  a  furnace  with  a  revolving  hearth  (Pernot  fur- 
nace). They  are  now  generally  referred  to  as  the  Bell-Krupp 
pig  washing  process,  and  the  special  addition  of  oxide  of  man- 


384  PURIFICATION  PROCESSES. 

ganese  is  dispensed  with  as  unnecessary.  The  product  is  called 
wash  metal,  washed  metal,  or  washed  pig. 

Slag  processes  are  those  in  which  molten  slag  is  employed, 
and  pig  washing  should  properly  be  included.  In  the  Talbot 
slag  process  a  basic  slag  consisting  of  iron  oxide  and  lime  is  first 
made  in  a  regenerative  furnace  and  is  then  poured  into  a  vessel 
of  suitable  form  (like  a  ladle)  so  it  forms  a  deep  column.  The 
molten  pig  to  be  treated  is  poured  on  top  of  this  column  through 
which  it  sinks  and,  during  its  passage,  a  considerable  quantity 
of  silicon  is  removed,  together  with  some  of  the  carbon  and 
phosphorus.  The  treated  metal  is  then  transferred  to  a  basic 
open  hearth  furnace,  and  the  purification  completed  in  the 
usual  way.  The  Knoth  slag  process  was  designed  especially 
for  use  in  connection  with  the  basic  open  hearth  process,  to 
effect  a  preliminary  purification.  The  molten  slag  from  the 
previous  heat  is  transferred  to  a  ladle  or  other  suitable  receptacle, 
and  lime  and  other  basic  materials  are  added  to  give  it  the  proper 
composition.  It  is  then  returned  to  the  regular  furnace  on  top 
of  the  next  charge  of  molten  metal.  S.  B.  Sheldon's  process 
appears  to  be  very  similar  to  that  devised  by  Knoth.  The  slag 
at  the  end  of  the  refining  operation  is  transferred  to  an  auxiliary 
furnace  where  fresh  basic  material  is  added,  the  whole  made  fluid, 
and  then  put  back  into  the  original  furnace  for  the  next  operation. 

Following  are  brief  descriptions  of  processes  which  have 
been  suggested  and  tried  from  time  to  time  with  varying  degrees 
of  success. 

Aubertin  and  Boblique's  process  had  for  its  object  dephos- 
phorization  by  the  action  of  alumina  or  fusible  aluminates, 
in  puddling  or  in  some  steel-making  process,  it  being  claimed 
that  phosphate  of  alumina  was  more  stable  in  the  'presence  of 
silica  than  the  phosphate  of  lime  or  magnesia. 

Bacon  and  Thomas'  process  was  designed  for  the  removal 
of  silicon  from  pig  iron  by  melting  it  in  a  cupola  with  the  addi- 
tion of  oxide  of  iron  and  limestone. 

Win.  Baker's  process  consists  in  blowing  air  on  the  surface 
of  molten  pig  as  it  flows  from  the  blast  furnace  in  a  specially 
designed  trough. 

In  Ball  and  Wingham's  process  molten  pig  iron,  high  in  sulphur, 
was  treated  with  potassium  cyanide,  sodium  carbonate,  and 
potassium  carbonate,  either  singly  or  together,  and  in  some 
reported  analyses  the  elimination  of  sulphur  varied  from  83  to 
100%. 

Bell's  refining  process,  the  product  of  which  was  to  be  used 
in  puddling,  consisted  in  oxidizing  the  silicon  in  a  Bessemer 
converter,  carbonaceous  matter  being  introduced  with  the 
blast,  or  spiegel  added,  if  there  was  danger  of  removing  too 
much  of  the  carbon,  so  the  phosphorus  would  not  be  properly 
eliminated  in  the  puddling  operation.  The  blown  metal  was 
to  be  used  molten. 

Brinell's  process  is  a  modification  of  the  Ellershausen  process 
(see  below).  An  ingot  mold  is  partly  filled  with  molten  pig 
iron,  and  when  solidification  is  about  to  take  place  a  quantity 


PURIFICATION  PROCESSES  385 

of  fine  ore  is  thrown  in  until  the  mold  is  full.  The  ingots  so 
produced  are  intended  to  be  used  in  the  open  hearth  process 
in  place  of  ordinary  pig  iron. 

Brown's  process  for  "neutralizing"  phosphorus  by  the  addition 
of  bichromate  of  potash  is  absurd. 

Budd's  process  for  removing  silicon  consisted  of  running  the 
metal  from  a  blast  furnace  into  shallow  pans  lined  with  a  dried 
paste  of  iron  ore;  in  another  process,  a  proportion  of  sodium 
nitrate  was  mixed  with  the  iron  ore. 

Bull's  process  was  designed  to  effect  dephosphorization  in 
either  the  Bessemer  or  the  open  hearth  process  by  blowing 
steam  through  the  bath.  It  was  claimed  that,  after  the  other 
impurities  had  been  removed,  the  steam  reacted  with  the  phos- 
phorus forming  a  volatile  phosphide  of  hydrogen.  Owing  to 
the  chilling  action  of  the  steam,  the  process  was  not  successful. 
Chute's  process  (recently  patented)  would  seem  to  be  nothing 
but  an  application  of  the  Ellershausen  process  (see  below),  his 
claim  of  discovery  being  "that  by  adding  powdered  ore  to  a 
stream  of  high-silicon  pig  iron  flowing  in  a  runner  to  the  pig 
beds  that  the  silicon  and  manganese  were  reduced  in  amount." 
The  process  was  to  be  used  in  connection  with  the  open  hearth 
process,  the  metal  being  added  in  a  molten  condition. 

In  the  Detmold  process  pig  is  melted  in  a  reverberatory 
furnace  similar  to  that  used  for  puddling,  and  air  is  blown  on 
the  surface. 

A.  de  Vathaire  suggested  the  use  of  cyanide  of  barium  or 
other  alkaline  earth  to  effect  desulphurization.  The  opera- 
tion was  to  be  performed  in  a  non-oxidizing  atmosphere,  pref- 
erably in  a  revolving  drum  lined  with  carbon  or  lime. 

The  distillation  process,  so  called,  was  performed  in  a  crude 
form  of  blast  furnace:  before  tapping,  the  tuyeres  were  inclined, 
and  the  blast  directed  upon  the  molten  pig  iron  in  the  hearth. 
Eaton's  process  was  claimed  to  effect  the  removal  of  phos- 
phorus, carbon,  and  silicon  from  planed  bars  of  cast  iron  by 
immersing  them  in  fused  alkaline  carbonates. 

The  Ellershausen  process  consists  in  treating  the  molten 
metal  flowing  from  a  blast  furnace  with  oxides  lining  the  run- 
ners, which  effects  a  partial  removal  of  the  silicon  and  carbon 
(probably  some  of  the  phosphorus  and  manganese  also).  The 
process  was  designed  originally  for  treating  pig  to  be  used  for 
puddling.  A  modification  has  occasionally  been  employed 
abroad  in  foundries,  where  a  certain  amount  of  silicon  is  re- 
moved by  throwing  fine  ore,  previously  heated  and  dried,  upon 
the  stream  of  metal  as  it  flows  out  of  the  cupola. 

In  Fament's  process  phosphorus  and  sulphur  were  to  be 
removed  from  any  grade  of  iron  by  treating  it  in  heated  retorts 
with  a  current  of  hydrogen. 

Farrar's  process  consisted  in  treating  pig  with  a  mixture  of 
sal  ammoniac,  ferrocyanide  of  potash,  and  manganese  (oxide?). 
Garnier's  process  for  dephosphorizing  is  practically  identical 
with  present  basic  open  hearth  practice.     It  consisted  in  charging 
lime  and  ore  before  the  other  materials. 
25 


386  PURIFICATION  PROCESSES 

James  Gregory  and  William  Green  claimed  that,  by  allowing 
broken  or  granulated  pig  iron  to  remain  in  water  for  some  time, 
it  was  made  better  and  tougher. 

Fernand  Hamoir's  process  was  for  refining  pig  iron  previous 
to  puddling.  The  pig,  while  being  tapped  from  the  blast  fur- 
nace, was  to  be  subjected  to  a  jet  of  air  derived  from  the  blast 
used  for  the  furnace. 

J.  Haythorne's  process  was  evidently  to  be  used  in  connec- 
tion with  the  puddling  process,  and  would  seem  to  have  been 
based  upon  questionable  principles.  While  the  metal  was 
molten,  he  added  a  mixture  of  dioxide  of  manganese,  oxide  of 
tin,  zinc,  or  lead  (!),  quicklime,  potassa  or  soda,  saltpeter  or 
ammonia,  and  brick  dust  or  calcined  clay. 

In  Heaton's  process  nitrate  of  soda  was  placed  in  the  bottom 
of  a  ladle  or  other  suitable  vessel,  being  kept  in  place  by  an 
iron  grating,  and  the  molten  pig  iron  was  poured  on  top.  It 
was  claimed  that  the  action  of  the  nitrate  removed  some  of 
the  phosphorus,  all  of  the  silicon,  and  nearly  all  of  the  sulphur. 

The  Henderson  process,  as  originally  applied  to  the  puddling 
process,  consisted  in  adding  fluorspar  and  titaniferous  iron 
ore  to  the  slag,  with  the  idea  that  the  impurities  would  pass 
off  as  volatile  fluorides.  At  Birmingham,  Ala.,  a  modification 
(Henderson  steel  process)  was  used  for  a  time  in  making  steel 
from  phosphoric  pig.  The  molten  pig  was  first  desiliconized 
and  partly  decarburized  in  an  auxiliary  chamber  of  a  special 
furnace,  and  was  then  run  into  a  basic  lined  furnace  and  treated 
with  dolomite  and  fluorspar.  It  would  appear  that  the  de- 
phosphorization  was  due  to  the  dolomite  rather  than  to  the 
fluorspar. 

Heerzeele  and  Paulis  attempted  to  purify  pig  (and  to  make 
steel)  by  heating  it  in  contact  with  steam. 

Marcus  Lane's  process  consisted  in  running  the  fused  metal 
from  a  melting  furnace  into  a  special  refining  furnace,  so  placed 
that  the  metal,  on  entering,  had  a  rotary  motion.  This  motion 
was  continued  by  means  of  a  blast  striking  the  metal  at  an 
angle  which  also  served  to  decarburize  it.  As  this  action  was 
apt  to  be  too  rapid,  carbon  was  added  at  intervals  to  give  time 
for  the  impurities  to  be  removed. 

In  J.  G.  Martien's  process  the  molten  metal  from  the  blast 
furnace  or  the  refinery  furnace  passed  through  gutters  where 
jets  of  air  or  steam  were  blown  up  through  it. 

The  Massenez  process  (Hoerde  process  or  Hilgenstock 
process)  for  desulphurizating  is  based  upon  the  fact  that  sulphur 
combines  with  manganese  in  preference  to  iron,  the  resulting 
manganese  sulphide  being  insoluble  in  the  molten  iron,  and 
therefore  passes  off  into  the  slag  if  sufficient  time  is  allowed. 
Pig  iron,  high  in  sulphur  and  low  in  manganese,  is  mixed  with 
pig  containing  a  considerable  proportion  of  manganese  (ferro- 
manganese  may  also  be  used)  both  being  in  the  molten  condi- 
tion. A  modification  consists  in  charging  oxide  of  manganese 
in  a  bath  of  metal,  part  of  the  manganese  being  reduced  and 
effecting  the  removal  of  the  sulphur. 


PURIFICATION  PROCESSES  387 

J.  B.  Nau's  process  is  designed  to  purify  pig  to  a  certain 
extent  by  running  it  into  a  cupola  of  special  construction  filled 
with  lumps  of  iron  ore  and  lime  previously  heated,  the  metal 
being  tapped  out  after  a  few  minutes. 

Parry  melted  wrought  iron  in  a  cupola  or  blast  furnace  and 
repuddled  it  to  obtain  a  further  elimination  of  phosphorus 
and  sulphur,  sometimes  repeating  these  operations.  He  em- 
ployed a  special  form  of  cupola  in  which  one  tuyere  was  hori- 
zontal, while  another,  at  the  opposite  side,  was  inclined  down- 
ward to  obtain  a  very  high  temperature  at  the  bottom  of  the 
furnace.  He  also  used  a  reservoir  or  vessel  provided  with  a 
number  of  sets  of  tuyeres  in  which  the  carburized  metal  could 
be  softened  by  jets  of  air  from  the  bottom  or  on  top. 

Peckham's  process  was  intended  for  the  purification  of  iron  and 
steel  in  a  Catalan  forge  or  puddling  furnace.  It  consisted  in 
removing  the  impure  cinder  as  fast  as  formed,  and  replacing  with 
a  pure  slag,  a  flux  being  used  for  thinning  when  the  slag  was  too 
viscous. 

Charles  Peter's  process  consisted  essentially  in  the  use  of  a 
small  reverberatory  furnace  at  the  top  of  a  special  narrow 
cupola  of  which  it  formed  a  part.  As  the  iron  was  melted  in 
the  former  it  fell  in  granules  through  the  latter  where  it  was 
acted  upon  by  the  air  which  entered  the  tuyeres  at  the  bottom 
end. 

In  Prince's  process,  cast  iron  is  treated  in  a  ladle  by  blowing 
air  through  it,  and  it  is  claimed  that  30  to  50%  of  the  sulphur  is 
removed  by  causing  it  to  unite  with  manganese  oxide  and  so 
pass  into  the  slag;  ferro-manganese  may  be  added  to  promote  this 
action. 

In  Jacob  Reese's  process  steel  (probably  wrought  steel) 
was  to  be  refined  with  an  oxidizing  blast  in  a  coke  refinery,  a 
layer  of  metallic  oxide  being  interposed  between  the  fuel  and 
the  metal. 

Rollet's  process  consisted  in  melting  pig  iron  with  a  slag 
composed  of  lime,  iron  ore,  and  fluorspar  in  a  basic  lined  cupola 
of  special  construction  in  which  the  tuyeres  were  so  arranged 
that  the  conditions  could  be  made  oxidizing  or  reducing  as 
desired.  This  process  was  intended  to  be  auxiliary  to  some 
steel-making  process. 

The  Saniter  process  for  desulphurizing  depends  upon  the 
use  of  calcium  chloride  in  a  slag  containing  a  high  proportion 
of  lime,  the  principal  action  of  the  calcium  chloride  being, 
apparently,  to  render  the  slag  fluid.  Fluorspar  is  also  added 
for  this  purpose.  It  may  be  used  in  treating  (a)  molten  pig 
iron  in  a  ladle  before  it  is  cast  into  pigs,  and  (6)  in  the  basic 
open  hearth  process  or  the  basic  Bessemer  process. 

Thomas  Shaw's  process  is  for  purifying  pig  iron  by  directing 
a  jet  of  dry  steam  upon  it  as  it  flows  out  of  a  cupola  furnace. 

The  Sherman  process,  like  Brown's,  had  for  its  object  "neu- 
tralizing" but  not  removing  the  phosphorus  in  steel,  and  is 
equally  absurd. 

Siemens'   purifying  process  consisted  in  heating  iron  oxide 


388  PURIFICATION  PROCESSES— PUT  ON 

spread  uniformly  over  the  hearth  of  an  open  hearth  furnace, 
followed  by  or  mixed  with  scrap  metal  or  puddled  iron.  These 
were  heated  to  a  white  heat,  and  molten  pig  iron  added.  The 
partially  purified  metal  was  then  run  irxto  another  open  hearth 
furnace  and  finished  as  usual. 

In  Smyth's  process  pig  iron  was  purified  in  a  Bessemer  con- 
verter by  introducing  various  chemical  compounds  with  the 
blast. 

B.  P.  Stockman's  process  is  similar  to  that  of  Heaton  (see 
above).  It  effects  a  preliminary  refining  by  running  molten 
pig  iron  upon  a  mixture  of  nitrate  of  soda,  magnetic  iron  oxide, 
common  salt,  and  black  oxide  of  manganese  (manganese  dioxide) 
contained  in  a  suitable  vessel.  The  action  is  very  violent 
and  as  soon  as  it  is  over  the  metal  is  finished  in  an  open  hearth 
furnace  in  the  usual  way. 

O.  Thiel,  one  of  the  originators  of  the  Bertrand-Thiel  process, 
refines  pig  iron  in  a  stationary  open  hearth  furnace,  using  a 
basic  oxidizing  slag  in  a  manner  very  similar  to  Surzycki's 
modification  of  the  Talbot  process  (see  page  316),  there  being 
a  number  of  tap  holes  at  different  levels,  and  only  a  portion 
of  the  charge  being  tapped  out  each  time,  which  is  finished  in 
another  furnace;  the  charge  may  also  be  finished  in  the  same 
furnace. 

E.  A.  Uehling's  process  consists  in  treating  molten  cast  iron 
while  in  the  ladle  with  various  materials  to  eliminate  impurities. 

E.  von  Maltitz  refines  molten  pig  iron  by  putting  it  in  a  ladle 
or  other  vessel  and  covering  it  with  a  basic  slag;  it  is  caused 
to  circulate,  and  a-jet  of  air  is  directed  against  the  surface  under 
the  slag  covering. 

Walrand's  process  is  intended  to  effect  dephosphorization  of 
a  bath  by  successive  removals  of  the  basic  slag  and  further 
additions  of  iron  oxide  and  lime. 

Warner's  process  is  somewhat  similar  to  that  of  Heaton 
(see  above),  nitrate  of  soda  being  replaced  by  ground  lime, 
soda  ash  (crude  sodium  carbonate),  and  small  amounts  of 
other  materials,  upon  which  the  molten  pig  iron  is  run,  to  be 
later  cast  in  molds  when  the.  purifying  action  is  complete; 
this  was  stated  to  require  about  10  minutes. 

Wellman  and  Schwab's  process  was  to  effect  a  preliminary 
partial  refinement  of  pig  iron  in  a  basic-lined  mixer  or  other 
suitable  vessel  in  which  the  metal  ccfuld  be  kept  molten.  Lime 
and  ore  were  added  and  at  intervals  portions  of  the  bath  were 
removed  and  used  in  the  regular  open  hearth  process. 

J.  G.  Willans'  process  does  not  seem  to  possess  any  special 
novelty.  Pig  iron,  in  contact  with  carbonaceous  matter,  is 
melted  in  a  cupola,  a  small  amount  of  silicon  being  removed, 
but  probably  not  any  phosphorus. 

Purifying  Process. — One  in  which  impurities  are  removed. 
Purity  of  Chemicals.  —See  page  89. 
Purple  Ore. — See  page  245. 
Purple  Temper. — Oxide  color:  see  page  230. 
Put  On.— Of  the  blast,  to  start. 


PYRAMIDAL  CLEAVAGE— PYRRHOTITE          389 

Pyramidal  Cleavage. — See  page  1 24. 

Pyramidal  System. — Of  crystallization:  see  page  120. 

Pyrheliometers. — See  page  207. 

Pyrite. — See  page  245. 

Pyrocrystalline. — See  page  122.. 

Pyroelectrplysis. — See  page  89. 

Pyrognomic. — See  page  204. 

Pyrolusite. — MnO2;  an  ore  of  manganese  employed  in  the  manu- 
facture of  ferro-manganese. 

Pyrolysis. — See  page  204. 

Pyrometallurgy. — Where  heat  is  applied  to  induce  the  desired  reac- 
tion, usually  by  causing  partial  or  complete  fusion. 

Pyrometamorphism. — See  page  122. 

Pyrometer.— See  page  205. 

Pyrometer  Effect. — See  page  203. 

Pyrometric  Scale. — See  page  204. 

Pyrometry. — See  page  205. 

Pyromorphous. — See  page  122. 

Pyrophoric. — See  page  204. 

Pyrophotometer. — See  page  208. 

Pyroscope. — See  page  208. 

Pyrrhotite. — See  page  245. 


Q 

Quadratic  System. — Of  crystallization:  see  page  120. 
Quadravalent. — See  page  86. 
Quadruple  Puddling  Furnace. — See  page  376. 
Qualitative  Analysis. — See  page  82. 

Quality. — (i)  The  suitability  of  a  material  for  the  purpose  for 
which  it  is  intended;  (2)  by  common  acceptation  (a)  the  process 
by  which  steel  is  manufactured  (e.g.,  open  hearth  steel)  and  (6) 
the  purpose  for  which  it  is  intended  (e.g.,  boiler  steel). 
Quality  Figure;  Formulae. — See  page  340. 
Quality  Steel. — See  page  443. 
^  lantitatiye  Analysis. — See  page  82. 
ititative  Microscopy. — See  page  284. 
irternary  Alloy. — See  Alloy. 

jrnary  Compound. — See  page  88. 

Steels. — See  page  443. 

ternary  System. — Of  crystallization :  see  page  1 20. 
ji  Tempered. — See  page  231. 
ich  Bend  Test— See  page  476. 

lenching. — (i)  Of  coke:  see  page  96;  (2)  of  steel:  see  page  227. 
lenching  Bath. — See  page  227. 
Quenching  Charge.— See  page  233. 
Quenching  Hardening. — See  page  227. 
Quenching  Medium. — See  page  227. 
Quenching  Temperature. — See  page  227. 
Quick  Cement. — See  page  67. 
Quick  Lime. — See  pages  175  and  396. 
Quick  Speed  Steel.— See  page  446. 
Quincke's  Hypothesis. — Of  foam  cells:  see  page  121. 


R 

R. — (i)  Reaumur  scale:  see  page  204;  (2)  to  indicate  a  rising 
temperature:  see  page  205 

Ra. — Chemical  symbol  for  radium:  seepage  84. 

Rb. — Chemical  symbol  for  rubidium:  see  page  84. 

Rh. — Chemical  symbol  for  rhodium:  see  page  84. 

Ru. — Chemical  symbol  for  ruthenium:  see  page  84. 

Raapke  Converter. — See  page  24. 

Rabble. — An  iron  instrument  resembling  a  hoe  used  to  stir  a 
metallic  bath  on  the  hearth  of  a  furnace;  sometimes  called  clot 
Eng.),  rarely,  rake. 

Rabble  Plate. — An  iron  plate  welded  to  the  end  of  a  rod  to  form  a 
rabble. 

Rabbling  Hole. — See  page  375. 

Rack. — A  mechanical  device  for  transmitting  power,  consisting  of  a 
long  bar  (generally  of  cast  steel)  on  one  surface  of  which  are 
teeth  which  engage  with  those  of  a  pinion  which  it  rotates  or  by 
which  it  is  moved.  It  is  commonly  employed  for  regulating 
the  height  of  the  top  roll  in  a  blooming  mill,  etc. 

Radial  Crystals. — Forming  a  radiating  structure:  see  page  125. 

Radiant  Energy;  Heat. — See  page  200. 

Radiating  Arc. — See  page  153. 

Radiating  Structure. — See  page  125. 

Radiation. — (i)  General:  see  page  200;  (2)  law  of:  see  page  200. 

Radiation  Curve. — See  page  200. 

Radiation  Furnace;  Heating. — (i)  Electric  furnace:  see  page  153; 
(2)  heating  furnace:  see  page  183. 

Radiation  Pyrometer. — See  page  207. 

Radical.— In  chemistry:  see  page  87. 

Radio-Balance. — See  page  207. 

Radiograph.— See  page  285. 

Radiometer.— See  page  205. 

Radiomicrometer.— See  page  205. 

Ragging.— See  page  407. 

Rail  Failures.— "Because  of  the  increased  attention  now  being 
given  to  the  rail  question  it  is  important  that  the  distinction 
between  rail  failures  and  broken  rails  be  clearly  understood  by 
the  public  as  well  as  by  railway  men.  Failed  rails  as  reported  by 
the  railways,  comprehend  all  rails  removed  from  the  track 
because  of  defects,  including  those  broken;  those  having  crushed 
or  split  heads,  broken  bases,  etc.  Many  of  these  defects  appear 
gradually,  affording  ample  opportunity  for  removal  of  the  rail 
before  complete  failure,  and  seldom  causing  serious  accidents. 
It  is  only  the  rails  actually  broken,  and  but  a  small  proportion  of 


3Q2  RAILER— RECALESCENCE  CURVE 

these,  which  give  rise  to  accidents.  An  analysis  of  the  failures 
reported  in  a  tonnage  aggregating  1%  million  tons  shows  but 
35%  of  the  rail  failures  reported  can  be  properly  classed  as 
rail  breakers"  (Ry.  Age  Gaz.,  May  24,  1912,  p.  1143). 

Railer. — A  kind  of  buggy  or  car,  without  sides,  for  carrying  ingots, 
etc. 

Raising  Hammer. — See  Hammer. 

Rake. — (i)  Of  shears:  see  page  412;  (2)  a  rabble  (rare). 

Ramage  Process. — See  page  166. 

Ramdohr  Process. — See  page  145. 

Ramming. — See  page  296. 

Ramming  Block. — See  page  300. 

Ramsbottom  Reversing  Mill. — See  page  408. 

Ramshorn  Test. — See  page  476. 

Rapid  Cement. — See  page  67. 

Rapid  Combustion. — See  page  202. 

Rapid  Tool  Steel.— See  page  446. 

Rapping;  Rapping  In. — Of  patterns:  see  page  296. 

Rare  Metal  Couple. — See  page  209. 

Rash. — On  sheets:  see  page  430. 

Rat  Tail.— See  page  17. 

Ratch. — See  page  508. 

Rate  of  Combustion. — See  page  203. 

Rating  of  a  Rolling  Mill. — See  page  410. 

Ratiometer. — See  page  208. 

Rational  Formula. — See  page  86. 

Rattle  Barrel.— See  page  58. 

Raw. — (i)  Material  in  its  natural  state,  or  as  produced,  without  any 
subsequent  treatment,  e.g.,  ores  which  are  not  roasted,  or  iron 
which  has  not  been  refined;  (2)  of  cement  bars:  see  page  71. 

Raw  Coal  Iron  (rare). — Pig  iron  smelted  with  coal. 

Raw  Gas.— See  page  33. 

Raw  Limestone. — See  Flux. 

Raw  Steel. — Natural  steel:  see  page  304. 

Raw  Steel  Processes. — See  pages  76  and  78. 

Rawson  Process. — See  page  371. 

Razor  Temper.— See  Temper. 

Reaction. — (i)  In  chemistry:  see  page  86;  (2)  in  connection  with 
stresses:  see  page  336.  „ ..: 

Reaction  Slag.— See  Slag. 

Reaction  Velocity  Theory. — Of  passivity:  see  page  364. 

Reactivity. — Ability  to  react. 

Ready  Iron. — In  puddling:  see  page  376. 

Reagent- — See  page  86 

Reaumine. — "Iron  of  Reaumur:"  name  suggested  for  malleable 
cast  iron. 

Reaumur  Iron. — See  page  257. 

Reaumur  Method.- — Of  quenching:  see  page  229. 

Reaumur  Process. — See  page  258. 

Reaumur  Scale.- — See  page  204. 

Recalesce;  Recalescence. — See  page  265. 

Recalescence  Curve. — See  page  267. 


RECALESCENT  POINT— RECARBURIZATION      393 

Recalescent  Point.— See  page  265. 

Recarbonization. — Recarburization,  q.v. 

Recarburization. — Sometimes  called  recarbonization ;  in  its 
special  sense,  adding  carbon  in  some  form  to  metal  (partially) 
decarburized  in  some  steel-making  process  to  obtain  the  proper 
percentage  of  carbon  in  the  finished  steel;  also  used  as  a  general 
term  for  the  addition  of  all  material  used  to  give  steel  the  de- 
sired composition  and  to  effect  its  deoxidation.  In  the  latter 
sense  it  is  perhaps  preferable  to  call  this  material  additions 
(also  called  recarburizing  additions,  final  additions,  or  finishing 
metal).  To  indicate  some  particular  material  its  name  is 
prefixed,  e.g.,  manganese  addition.  The  additions  are  frequently 
made  cold,  generally  in  the  ladle  (ladle  additions),  but  if  they 
are  in  such  large  amounts  that  there  is  danger  of  chilling  the  metal 
they  may  be  (a)  preheated  to  a  cherry  red,  (b)  melted,  or  (c)  added 
in  the  furnace  (furnace  additions),  either  wholly  or  in  part.  The 
practice  of  adding  pig  iron  in  the  furnace  to  increase  (bring  up  or 
fetch  up)  the  percentage  of  carbon  (called  in  England  pigging 
back  or  pigging  up),  is  usually  restricted  to  the  acid  processes  on 
account  of  the  danger  of  rephosphorization.  The  ladle  additions 
are  made  while  the  heat  is  being  tapped,  and  an  important 
point  is  to  get  them  in  before  much  of  the  slag  has  appeared. 
Darby's  process  of  recarburizing  consists  in  adding  fine  coal 
to  the  metal  as  it  runs  into  the  ladle;  a  hopper  and  funnel  are 
generally  employed  to  control  the  rate  of  flow  of  the  coal.  In 
the  Dudelingen  process  (Meyer  process)  fine  coal,  with  about 
10%  of  milk  of  lime  as  a  binder,  is  pressed  into  bricks  and  dried, 
these  being  thrown  into  the  ladle;  it  was  devised  for  use  in  the 
manufacture  of  basic  Bessemer  steel.  Robert  Mushet's  process 
consisted  in  adding  spiegel  or  some  other  form  of  manganese. 
Nickel,  as  nickel  scrap  or  ingot  nickel,  is  usually  charged  at  the 
beginning  of  the  heat.  Other  materials,  as  a  rule,  are  added 
toward  the  end  of  the  heat  or  in  the  ladle.  Ferro-titanium  and 
ferro-vanadium  (claimed  to  have- the  property  of  combining  with 
and  removing  nitrogen)  are  put  into  the  ladle  after  the  other 
additions. 

Following  is  a  general  classification: 
I.  Carbon  additions : 

1.  Pig  iron: 

(a)  Solid:  added  in  the  furnace. 

(b)  Molten:  added  in  the  furnace  or  in  the  ladle. 

2.  Coal  or  coke  (crushed): 

(a)  In  paper  bags. 

(b)  Fed  from  a  hopper. 

(c)  In  briquettes. 

3.  Contained    in    other    additions    (e.g.,    ferro-man- 
ganese). 

II.  Manganese  additions : 

4.  Ferromanganese. 

5.  Spiegel  (usually  molten). 

6.  Silico-spiegel. 

7.  Ordinary  pig  iron. 


394          RECARBURIZING— REELING  MACHINE 

III.  Silicon  additions : 

8.  Ferro-silicon  (10  to  16%  silicon). 

9.  Ferro-silicon  (50%  silicon  or  over). 

10.  Carborundum. 

11.  Silico-spiegel. 

12.  Ordinary  pig  iron. 

IV.  Sulphur  additions : 

13.  Roll  sulphur. 

14.  High  sulphur  pig  iron  (rare). 

V.  Phosphorus  additions : 

15.  Ferro-phosphorus  (up  to  about  30%  phosphorus). 

16.  Minerals   containing   phosphorus    (as    P2O5,    part 
of  which  is  reduced). 

VI.  Special  additions: 

Chromium,  tungsten,  etc.;  see  page  351. 

Recarburizing  Additions.— See  Recarburization. 

Receiver. — See  Mixer. 

Reciprocal  Proportions.— Law  of:  see  page  85. 

Reciprocating  Mill,  Brown's. — See  page  417. 

Recording  Extensometer. — See  page  471. 

Recording  Pyrometers. — See  page  210. 

Recover;  Recovery. — See  pages  96  and  333. 

Recrystallization;  Of  Deformed  Iron.— See  pages  122  and  216. 

Recuperation. — See  page  204. 

Recuperative  Furnace. — See  page  183. 

Red  Charcoal.— See  Charcoal. 

Red  Fossil  Ore.— See  page  244. 

Red  Hard  Sheet.— See  page  430. 

Red  Hardness. — See  page  446. 

Red  Heat. — Temperature  color:  see  page  210. 

Red  Hematite ;  Iron  Mine ;  Iron  Ore ;  Red  Mine  Stone. — See  page 

243- 

Red  Ochre. — See  page  244. 
Red  Short;  Shortness.— See  Brittleness. 
Red  Short  Ore.— See  page  243. 
Red  Slag  Ironstone  (Eng.).— See  page  243. 
Reduction. — (i)  In  chemistry:  see  page  88;  (2)  draft,   in  rolling: 

see  page  407;  (3)  lowering  the  amount  of  a  constituent,  e.g.,  the 

reduction  of   (the  percentage  of)   carbon  in  a  metallic  bath. 
Reduction  of  Area. — See  pages  336  and  472. 
Reduction  Ring. — See  Cold  Working. 
Reed  Process. — (i)  For  electrolytic  iron:  see  page  166;  (2)  for 

pickling,  q.v. 
Reediness  (Eng.). — In  piled  iron,  a  tendency  when  rolled  (into 

plates)  to  split  sideways. 
Reek  (Eng.). — To  smoke  the  inside  of  molds. 
Reel. — A  device  for  coiling  up  small  sections,  such  as  wire,  hoop,  etc. 

which  may  be  operated  by  hand  or  by  power. 
Reeling  Machine  (Eng.). — Cross  rolls  for  straightening:  see    page 

490. 


REESE  MILL— REFRACTORIES  395 

Reese  Mill. — See  page  419. 

Reese  Process. — (i)  Direct  process:  see  page  145;  (2)  galvanizing 

process:  see  page  370;  (3)  refining  process:  see  page  387. 
Refined  Bar. — See  page  378. 
Refined  Cast  Iron. — See  page  383. 
Refined  Grain. — See  page  214. 
Refined  Iron. — See  page  378. 
Refined  Metal. — See  page  383. 
Refined  Structure. — See  page  214. 
Refiner. — See  page  316. 

Refinery  (Refining) ;  Refinery  Hearth;  Process. — See  page  383. 
Refining  by  Hardening. — See  page  229. 
Refining  Heat. — See  page  214. 

Refining  Point;  Temperature. — Critical  point:  see  page  214. 
Refractory. — Capable  of  withstanding  high  temperatures  without 

fusing  or  softening. 
Refractories. — Refractory  substances  are  those  which  possess,  at 

least  in  some  degree,  the  following  qualities  (Diehl) : 

1.  Ability  to  prevent  heat  losses  through  radiation  (and  con- 
duction). 

2.  Ability  to  withstand  the  degree  of  heat  to  which  they  are 
subjected  without  altering  their  chemical  or  physical  relations. 

3.  Sufficient  hardness  to  prevent  abrasion  and  yet  not  spall. 

4.  Low  coefficient  of  expansion  and  contraction. 

5.  Inertness  to  the  chemical  reactions  taking  place. 

They  are  classified,  according  to  their  chemical  properties,  into 
acid,  basic,  and  neutral  refractories. 

Acid  refractories. — Sand:  Consists  essentially  of  silica, 
SiO>2,  and  is  usually  obtained  from  natural  deposits  in  fine 
grains,  sometimes  by  crushing  or  grinding  up  silicious  rocks. 
It  should  contain  not  over  10%  of  impurities  as  these  tend  to 
make  it  more  fusible,  iron  oxide  and  the  alkalies  being  the 
most  undesirable.  It  is  used  loose  for  lining  furnaces  and  in 
molding.  Silicious  rocks  (firestone,  ganister,  and  sandstone) 
are  composed  almost  entirely  of  silica,  and  may  be  used,  in 
their  natural  state,  in  large  pieces  or  lumps  (Eng.)  for  lining 
acid  converters  and  cupolas.  Their  principal  application, 
however,  is  in  the  manufacture  of  silica  bricks  or  Dinas  bricks, 
for  which  purpose  they  are  crushed  and  mixed  with  about  i 
to  2%  of  lime  as  a  binding  material,  moistened  with  water, 
molded,  dried,  and  then  burned  (i.e.,  heated)  at  a  very  high 
temperature,  during  which  they  expand  lineally  about  3%. 
Bricks  thus  made  are  also  designated  as  lime  Dinas  bricks  or 
English  bricks;  where  clay  up  to  about  10  to  20%  is  used  instead 
of  lime,  the  bricks  are  not  so  good  and  are  termed  clay  Dinas 
bricks  or  German  Dinas  bricks.  Particularly  with  new  or 
difficult  sections,  unequal  ramming  producing  a  variation  in  the 
density  of  the  green  brick  (before  burning),  results  in  cracks 
(fire  cracks)  due  to  unequal  expansion  when  the  brick  is  burned. 
Fused  silica,  produced  in  an  electric  furnace,  is  too  expensive 
to  use  except  for  certain  chemical  apparatus.  The  name 
ganister  was  first  applied  to  a  variety  of  sandstone  found  near 


396  REFRACTORIES 

Sheffield,  but  is  now  used  for  any  rock  very  high  in  silica. 
Silicious  clays  or  clays,  comprising  fireclay  and  loam  are  hy- 
drous silicates  of  alumina  resulting  from  the  decomposition  of 
feldspar;  pure  clay  or  kaolin  has  the  formula  A12O3,  2SiC>2, 
2H2O.  If  the  proportion  of  silica  is  higher  than  this  the  clays 
are  termed  acid  or  silicious ;  if  lower,  basic  or  aluminous. 
Fireclay  has  low  impurities  (lime,  magnesia,  iron  oxide,  and 
alkaline  oxides),  and  is  not  easily  fusible.  It  is  used  in  the 
manufacture  of  fire-bricks  or  fire-clay  bricks,  which  are  molded 
and  then  burned  at  a  high  temperature,  during  which  they 
shrink  lineally  about  8%,  the  amount  varying  with  the  nature 
of  the  clay.  Burnt  fireclay  is  called  chamotte  (French),  scha- 
mptte  (German),  and  grog  (English),  and  bricks  made  from  it, 
mixed  with  a  little  unburnt  clay  as  a  binder,  are  similarly  des- 
ignated. A  brick  made  with  part  silica  and  part  chamotte  is 
called  half -silica  or  half -chamotte  brick. 

Ball  stuff,  for  repairing  acid  linings,  consists  of  fireclay  mixed 
with  sand  or  loam  and  a  little  water  to  make  it  plastic.  Loam 
is  a  clay  containing  a  higher  percentage  of  silica  than  fireclay 
(say  over  70%)  which  makes  it  somewhat  more  fusible.  Accord- 
ing to  Mellor,  clays  and  shales  may  be  divided  into  refractory 
clays  which  soften  above  1500°  C.  (2730°  F.),  and  non-refractory 
clays  which  soften  below  this.  He  further  classifies  the  refrac- 
tory clays  into  (i)  low  grade  fireclay,  softening  between  1500  and 
1650°  C.  (2730  and  3000°  F.);  (2)  medium  grade  fireclay,  softening 
between  1650  and  1750°  C.  (3000  and  3180°  F.);  and  high  grade 
fireclay,  softening  only  above  1750°  C.  (3180°  F.).  This  softening 
point  is  to  be  determined  under  standard  conditions.  A  natural 
substance  known  as  infusorial  earth,  diatomaceous  earth,  or 
kieselguhr,  contains  a  fairly  high  percentgae  of  silica  (see  analysis 
below);  being  the  skeleton  of  tiny  organisms  (diatoms)  it  is 
extremely  porous,  hence  most  excellent  as  a  heat  insulator,  but 
it  is  not  suitable  to  resist  very  high  temperatures.  A  similar 
material  found  on  the  Pacific  Coast  is  called  celite;  it  is  ground 
and  made  into  bricks  known  under  the  trade  name  of  silocel 
bricks  and  used  for  hot  blast  stoves,  etc.  J.  W.  Richards 
mentions  a  material  of  similar  nature  found  in  Jutland,  called 
moler,  used  for  refractory  bricks. 

Basic  Refractories. — Oxides  of  iron,  either  natural  as  ore 
or  artificial  as  scale  or  cinder,  are  rather  easily  reduced  at  a 
high  temperature  in  the  presence  of  carbon,  etc.,  and  are  also 
fairly  fusible,  and  hence  are  employed  only  when  the  tem- 
perature is  comparatively  low,  e.g.,  for  the  lining  of  puddling 
furnaces  and  the  bottoms  of  some  heating  furnaces.  Lime 
and  magnesia  are  obtained  almost  entirely  as  the  minerals 
limestone,  magnesite,  and  dolomite.  Limestone,  CaCOs, 
when  burned  (calcined)  yields  lime,  CaO,  also  called  quick- 
lime or  burnt  lime,  which  tends  to  absorb  moisture  and  car- 
bonic acid  (i.e.,  to  slack  or  slake)  unless  kept  at  a  high  tem- 
perature. Except  for  the  bottoms  of  basic  converters  (mixed 
with  tar)  it  is  used  principally  as  a  flux.  Magnesite  MgCO3, 
when  burned  yields  magnesia,  MgO,  which  slacks  very  little 


REFRACTORIES  397 

and,  next  to  carbon,  is  probably  the  most  refractory  substance. 
Its  principal  use  is  for  making  bricks  (magnesia  bricks  or  mag- 
nesite  bricks)  for  which  purpose  it  is  crushed,  burnt  at  a  very 
high  temperature,  then  moistened  with  a  little  water,  molded, 
and  burnt  again,  a  small  amount  of  impurities  which  it  contains 
acting  as  the  binding  material.  It  may  be  either  massive  or 
crystalline;  the  former  occurs  in  serpentine  and  is  widely  dis- 
tributed, the  most  important  deposit  being  probably  in  Euboea 
Greece;  the  crystalline  variety  is  found  only  in  Austro-Hungary 
where  it  occurs  in  the  dolomite  to  which  it  owes  its  origin  in 
becoming  metamorphosed  (Morgenroth).  Dolomite,  CaMg 
(COa)2,  is  widely  distributed  in  this  country  and  hence  cheaper 
than  magnesite,  practically  all  of  which  must  be  imported. 
When  low  in  magnesia  it  is  sometimes  called  magnesian  lime- 
stone. When  burnt  it  does  not  slack  nearly  so  readily  as  lime. 
It  is  used  principally  in  this  country  as  a  lining  for  basic  open 
hearth  furnaces,  after  crushing,  and  either  calcined  or  raw; 
abroad  also  for  basic  Bessemer  converters,  crushed,  calcined,  and 
mixed  with  tar. 

Patented  substitutes  for  regular  dolomite  or  magnesite  have 
recently  been  placed  on  the  market  under  various  trade  names, 
some  typical  analyses  being  given  in  the  table  at  the  end  of  the 
article,  and  certain  processes  being  described  below.  These 
substitutes  usually  consist  of  some  form  of  magnesian  limestone  or 
dolomite  rock,  which  is  burned  once  or  twice,  and  frequently 
with  additions  of  some  form  of  limestone,  such  as  basic  slag. 
The  process  for  producing  magdolite  or  J.  E.  Baker's  double- 
burned  dolomite  is  described  in  the  patent  papers  as  follows :  Raw 
dolomite,  in  lumps  2  to  4"  in  diameter,  is  charged  in  a  cupola 
furnace  with  alternate  layers  of  coke  and,  after  burning  as 
in  ordinary  dolomite  burning,  is  crushed  and  screened  through 
about  a  %"  mesh.  The  product  thus  obtained  has  a  considerable 
percentage  of  ash,  coke,  and  fines  mixed  with  the  good  material; 
it  is  preferably,  without  further  treatment,  subjected  to  a  second 
burning  in  a  rotary  kiln.  By  subjecting  to  a  temperature  of 
about  2400°  F.  (1315°  C.)  the  coke  and  cinder  constituents  of  the 
mass  are  consumed,  and  the  finer  particles  of  dust  either  fused  or 
carried  away  by  the  draft.  The  dolomite  granules  are  subjected 
to  sufficient  heat  to  drive  off  any  volatile  matter  which  may  have 
remained  after  the  first  burning,  and  are  rendered  much  less 
pervious  to  moisture.  The  product  is  much  heavier  than  dolo- 
mite obtained  by  ordinary  burning  and  is  more  uniform  in  charac- 
ter. Syndolag  is  produced  according  to  the  patent  papers  as 
follows:  Dolomitic  limestone  is  crushed  to  about  %"  size,  put 
through  a  drier,  the  dust  screened  out,  and  the  granular  material 
fed  through  a  rotary  kiln,  under  conditions  similar  to  those  obtain- 
ing in  the  burning  of  Portland  cement.  In  the  kiln  the  material 
first  passes  under  the  direct  influence  of  a  hot  flame,  where  it  is 
raised  to  a  temperature  sufficiently  high  to  cause  incipient  fusion 
or  sintering.  This  temperature  should  be  around  2800°  F. 
(1535°  C.).  The  sintered  granules  of  dolomite  are  then  cooled 
in  a  rotary  cooler,  and  mixed  with  granulated  basic  open  hearth 


398   REFRACTORIES— REGENERATIVE  CHAMBER 

slag.  With  a  dolomite  running  40%  magnesia  (MgO),  a  mixture 
of  90  parts  of  dolomite  and  10  parts  of  slag  works  well.  Bauxite 
is  a  mineral  consisting  principally  of  alumina,  AlaOs  (which  should 
run  over  85%),  with  small  amounts  of  silica,  iron  oxide,  etc.,  as 
impurities.  It  is  usually  crushed  and  washed  before  using  but, 
owing  to  difficulties  in  preparation,  and  its  excessive  shrink- 
ing and  cracking,  it  finds  practically  no  employment  in  the  iron 
industry.  It  is  sometimes  made  into  bricks  (bauxite  bricks). 
Neutral  Refractories. — Chrome  iron  ore  or  chrpmite,  FeO, 
Cr2Os,  is  highly  refractory  and  is  generally  used  in  the  form 
of  bricks  (chrome  bricks),  ocassionally  simply  after  crushing. 
It  is  employed  to  make  a  separation  between  acid  and  basic 
linings  in  the  basic  open  hearth  furnace.  Carbon  is  the  most 
refractory  substance  known.  The  form  known  as  graphite 
is  found  natural  or  is  manufactured  in  the  electric  furnace. 
Only  the  natural  variety  is  used  for  making  graphite  crucibles 
(see  page  in).  Carbon,  usually  crushed  coke,  is  also  used 
in  the  manufacture  of  clay  crucibles.  It  is  sometimes  made 
into  bricks  (carbon  bricks),  with  pitch  or  tar  as  the  binding 
material.  A  deposit  of  carbon  is  found  in  the  bricks  forming 
the  lining  of  blast  furnaces  which  serves  to  protect  the  walls 
from  corrosion.  Carborundum  (silicide  of  carbon,  silicized 
carbon,  silicon  carbide),  SiC,  is  manufactured  in  an  electric 
resistance  furnace.  Aside  from  its  principal  use  as  an  abrasive, 
it  finds  some  application  as  a  refractory  owing  to  its  being  almost 
unaffected  by  chemical  reactions  (except  in  special  cases)  even 
at  high  temperatures.  Possessing  similar  properties  is  another 
form  called  silundum  which  may  be  of  two  varieties,  of  steel- 
gray  appearance  with  the  formula  SiC,  and  slate-green  with  the 
formula  Si^O.  Silfrax  a  silicized  carbon  is  also  very  similar  to 
carborundum,  being  obtained  by  the  action  of  vapors  of  silica 
or  silicon  on  solid  carbon.  It  is  claimed  to  possess  all  the  chem- 
ical and  heat  resisting  properties  of  carborundum  and,  in  addition, 
great  density  and  toughness.  Silit  is  the  name  given  to  material 
of  practically  the  same  nature,  which  may  consist  of  a  mixture  of 
silicon  carbide  and  free  silicon,  or  silicon  carbide  only,  prepared 
in  an  electric  furnace.  Fibrox  is  the  name  given  to  a  fibrous 
material  consisting  of  an  oxycarbide  of  silicon  without  any  defi- 
nite chemical  composition.  It  is  soft  and  resilient,  and  has  high 
insulating  properties  for  heat.  Vitricarbo  is  the  trade  name  for  a 
carbonaceous  refractory  material  which  contains  a  vitrifying 
ash  as  a  binder.  (See  table  of  analyses  on  next  page.) 

Refractory  Clays. — See  page  396. 

Refreshment. — See  page  333. 

Refrigerant;  Refrigerating  Agent. — See  page  200. 

Refroidissoir  (French). — A  cooling  chamber,  e.g.,  a  chamber  in 
which  iron  sponge,  produced  by  some  direct  process,  is  protected 
from  oxidation  during  cooling. 

Regeneration. — (i)  Of  a  cement:  see  page  67;  (2)  in  heating:  see 
page  203. 

Regeneration  Quenching. — See  page  228. 

Regenerative  Chamber. — See  pages  203  and  310. 


REFRACTORIES 


399 


2 

o 
o 

I 

M 

IO 

1 

O 
a 
2 

M    O   O    O\ 
^    10  00     d 

4    >0     W      M 

2222 

§2  2*  S 
O     M    OO 

t-    10 

«O     HI 

Ov   «    *   »    0    W 
«  ,    0    0    «    0   0 

10  vO   O    H    M   ° 
oo  oo               *** 

OooroOiOTf          HI    O    O    O    O 
O    to    ro   t^    HI    ro          t^toNW^O 

IO 

OMOOOO           OfONOO 

M 

o 

M 
g 

n  <$  ««  M 

1010          O    HI   O    N           r5OiMOf°POfOf° 
•*    O»            PO'tPOto            ^tOOlOOOOO 

CO   00 
t>.    00 
00    «*5    ^    O            Oi 

H      O      O      to              t^ 

*    0     N      °     3     H      M 

«   o  t~  t* 

"^  r~   Oi   ^ 

O 

O     ^t  00    00 

oo  oo    t-  0 

0            PINOOOOO101''1010 
W»4            t^Ou>-i^tOloOOOOOO 

4J^j               jj         *4J         *         *•         *         •         •-*J-4J4J-*J 

oo   d\  10  4 

p«    ^J- 

CO    »0 
to   ««   ">    ro    0    0 

O    ^     O    00    O     M 

£§  ^S"  " 

q 

1 

iOvOt~OioOt-oOM           Oro 

"•^0001040       oo 
•*  ^t       o            o 

o             o 

O    OOOOfONO           OO 

o  t- 

O      HI 

g^ 

O\    °-  00    00 

2  SS 

o 

too  « 

£ 

Mtvooo«ioMooa«ot^^-^ 

2  °  °?  §^ 

t^    O      M 

O-So-Ch^ttOOO     °     °     ^°     ^^^^ 

M      .0     M 

V 

| 

;         •    

:?:|J 
•g-3  3 

:       :    :       :    :    :    :  ^       :    :   : 

£ 

I    ij    j  :  I.IJ    i  M 

8  &  l'|  >.^il§ll|-l  SPji 

2^^*°^'_g|^§s§^o-a« 

llilillllHllill 

rt  -S    *J    •Sjp2*c|<4WW«isW    »*>  "^  /-s 
09  A  O  05  09  A  A  M  M  «  X  Q  !«  OT  X  Q 

8;  *  J  1      8 

£<v  £  £       ° 

•o  S  »  «  2  § 

Iflffl 

iJJAJS 

y 

T^     REGENERATIVE  CRUCIBLE— RESISTING      ' 

Regenerative  Crucible  Furnace. — See  page  183. 

Regenerative  Furnace. — See  page  183. 

Regenerative  Stove. — See  page  203. 

Regenerator. — See  pages  183  and  203. 

Regnault  Calorimetric  Pyrometer. — See  page  207. 

Regular  Cementite. — See  page  273. 

Regular  Coil.— See  Coil. 

Regular  System. — Of  crystallization:  see  page  120. 

Regulator  Test  Piece. — See  page  70. 

Reheated  Carbon. — See  page  272. 

Reheating.— Of  steel:  see  page  232. 

Reheating  Furnace. — See  pages  184  and  377. 

Reichinstein's  Theory. — Of  passivity:  see  page  364. 

Rejection. — Material  thrown  out  on  account  of  defects  arising  in 
the  course  of  manufacture. 

Relative  Deformation. — See  page  334. 

Relative  Elastic  Limit. — See  page  470. 

Relative  Hardness. — See  page  478. 

Relief  Polishing.— See  page  286. 

Remelting  Process. — Founding;  sometimes  a  purification  process. 

Removable  Bottom,  Holley's. — See  page  17. 

Removable  Top  Furnace. — See  page  313. 

Reniform  Iron  Ore. — See  page  244. 

Rennerfelt  Furnace. — See  page  162. 

Reoxidation. — Oxidation  of  metal  which  has  once  been  reduced, 
more  especially  in  connection  with  the  reducing  process  em- 
ployed, or  immediately  after  the  operation. 

Repeated  Stresses.— See  page  333. 

Repeated  Twinning. — See  page  1 24. 

Repeater;  Repeating  Mill. — See  page  416. 

Repetitive  Stressing. — See  page  482. 

Rephosphorization. — In  any  purification  process  where  phosphorus 
is  eliminated  and  taken  up  by  the  slag,  and  is  then  partially  or 
wholly  reduced  again  by  a  reaction,  generally  with  some  addition, 
and  reenters  the  metal. 

Repouring  Process. — A  process  in  which  metal,  partially  refined  in 
one  furnace  or  vessel,  is  run  into  a  ladle  and  then  poured  into 
another  furnace  or  vessel  to  be  finished:  see  page  21. 

Rerolling. — See  page  419. 

Reservoir. — See  Mixer. 

Reservoir  Cupola. — See  page  182. 

Residual. — Remaining;  as  the  percentage  of  impurities  which  are 
not  removed  in  a  purifying  process,  etc. 

Residual  Energy. — See  page  481. 

Residue  Analysis. — See  page  82. 

Resilience. — See  page  331. 

Resistance. — See  page  330. 

Resistance -Arc  Furnace. — See  page  153. 

Resistance  Furnace;  Heating. — See  page  153. 

Resistance  Pyrometer. — See  page  208. 

Resistance  Weld.— See  page  503. 

Resisting  Moment;  Shear.— See  page  337. 


RESISTOR— RINGING  TEST  40 1 

Resistor. — See  page  154. 

Resolve. — In  microscopy:  see  page  285. 

Resonance  Test. — See  page  483. 

Resquared  Plate. — See  page  433. 

Rest. — (i)  To  allow  material  to  remain  without  applying  any  load 

to  it  or  otherwise  disturbing  it;  (2)  in  a  rolling  mill;  see  page  415. 
Restitution,  Coefficient  of.— See  page  478. 
Restored  Steel. — See  page  226. 
Resulphurization. — The.  reabsorption  of  sulphur  by  metal  from 

which  it  has  been  removed,  usually  in  the  same  process. 
Retained  Carbon. — In  hardening:  see  page  279. 
Retardation.— (i)  In  the  cooling  of  alloys:  see  page  264;  (2)  of 

corrosion:  see  page  364. 
Retarded  Coke. — See  page  97. 
Retarded  Combustion. — See  page  202. 
Retention  Theories. — Of  hardening:  see  page  279. 
Retentive. — Able  to  hold,  i.e.,  prevent  subsequent  removal,  as  of 

slag  with  regard  to  phosphorus. 

Reticular  Structure;  Reticulated  Structure. — See  page  126. 
Retort  Coke. — See  page  95. 
Retort  Furnace. — See  page  184. 
Retort  Oven. — 'See  page  96. 
Returns  (Eng.). — Material  rejected  by  customers. 
Reverb eratory  Furnace. — See  page  182. 
Reversed  Mold. — See  page  300. 

Reversible  Alloy ;  Process ;  Transformation. — See  pages  265  and  327. 
Reversing  Class. — In  hardening:  see  page  279. 
Reversing  Mill. — See  page  408. 
Reversing  Overstrain. — See  page  282. 
Reviving  (obs.). — Producing  (reducing)  metal  from  its  ores  or  from 

its  oxidized  condition. 
Revolving  Screen. — See  Screen. 
Revolving  Top. — Of  a  blast  furnace;  see  page  32. 
Rewelded  Pipe. — See  page  490. 
Rhabdite. — See  page  292. 
Rhombic  Sulphur. — See  Sulphur. 
Rhombic  System. — Of  crystallization:  see  page  120. 
Rhombohedral  Cleavage. — See  page  124. 

Rhombohedral  (-ic)  System. — Of  crystallization;  see  page  120. 
Riband  (Eng.). — Ribbon  or  band. 
Rich;  Richness. — Of  pig  iron;  high  in  silicon. 
Rich  Iron. — See  page  343. 
Riddle. — In  molding;  see  page  301. 
Rider. — (i)  In  a  rolling  mill:  see  page  406;  (2)  of  a  testing  machine: 

see  page  469. 

Riemer  Hot  Top  Process. — See  page  61. 
Riepe  Process. — See  page  380. 
Rifled  Pipe. — See  page  490. 
Rigidity.— See  page  330. 
Ring. — (i)    In   blast  furnace  practice:  see  page  35;  (2)  in  cold 

drawing;  see  page  101. 
Ringing  Test.— See  page  483. 

26 


402  RINSING  BATH— ROLLING 

Rinsing  Bath.— See  page  507. 

Rinton  Process. — See  page  145. 

Ripper;  Ripping  Block. — In  wire  drawing:  see  page  508. 

Riser. — Of  castings:  see  pages  56  and  299. 

Rising  Casting. — See  page  57. 

Rising  Gate. — See  page  299. 

Rising  Head. — See  page  56. 

Rising  Steel.— See  page  55. 

Riveted  Pipe.— See  page  489. 

Roach  Belly  Core. — See  page  299. 

Roak.— See  Seam. 

Roasted  Red  Mine  (Eng.). — Roasted  hematite. 

Roasted  Steel. — See  page  226. 

Roasting. — (i)  In  briquetting;  see  page  44;  (2)  see  Ore. 

Roasting  Heap;  Mound;  Pile. — See  page  181. 

Robert  Converter. — See  page  24. 

Roberts-Austen  Equilibrium  Diagram. — See  page  272. 

Roberts-Austen  Recording  Pyrometer. — :See  page  210. 

Robertson  Process. — See  page  492. 

Robin's  Reagent. — For  etching;  see  page  287. 

Rochussen  and  Daelen  Process. — See  page  22. 

Rock  Sand  (Eng.). — The  debris  of  abraded  rock. 

Rock  Wool.— See  Slag  Wool. 

Rod. — Generally  understood  to  be  a  round  bar.  Standard  wire 
rods  are  round  bars  having  a  section  0.2  to  0.3"  diameter,  which 
are  coiled  in  bundles.  U.  S.  Government  limits  size  of  wire  rods 
to  No.  6  B.  W.  G.  or  0.203",  and  if  smaller  than  this:  wire. 

Rod  Casting  Process.— See  page  65. 

Rod  Mill. — See  page  415. 

Rodney  (Eng.).— See  page  377. 

Roebling  Gage. — See  page  187. 

Roechling-Rodenhauser  Furnace. — See  page  162. 

Roger  Process. — (i)  Direct  process:  see  page  145;  (2)  for  sulphur 
prints:  see  page  288. 

Rohl's  Reagent. — For  etching;  see  page  287. 

Rohnitz  Process. — See  page  78. 

Roke  (Eng.). — See  Seam. 

Rolls. — See  page  403. 

Roll-Knobbling. — See  page  369. 

Roll  Mark. — See  page  405. 

Roll  Scale.— See  Scale. 

Roll  Table.— See  page  407. 

Roller. — (i)  The  man  in  charge  of  a  rolling  mill:  see  page  430;  (2) 
a  metal  cylinder  mounted  on  a  shaft  which  is  driven  (live  roller) 
or  is  not  driven  (idle  roller  or  idler),  for  transporting  pieces  of 
steel,  etc.  When  a  live  roller  is  broken  it  is  called  a  dead  roller. 

Roller  Pot. — In  coating  sheets,  a  vessel  filled  with  molten  metal 
through  which  the  sheets  are  drawn  by  means  of  several  pairs 
of  rolls. 

Roller's  Side.— See  page  415. 

Rollet  Process. — See  page  387. 

Rolling;   Rolling   Mills. — Rolling   is   the   operation   of   reducing 


ROLLING 


403 


the  section  of  pieces  of  metal  by  passing  them  between  revolv- 
ing cylinders  termed  rolls.  A  rolling  mill  consists  essentially 
of  the  rolls  set  in  a  suitable  framework  to  support  them,  called 
housings,  standards  (Eng.),  or  holsters  (Eng.),  and  connected 
with  the  engine  by  pinions  and  spindles  as  will  be  described 
later. 

Rolls.— These  consist  of  (a)  a  middle  portion  called  the 
body  or  barrel  which  comes  in  contact  with  the  piece  being 
rolled;  (&)  the  ends  which  rest  in  the  bearings,  called  necks, 
journals,  or  rarely  spindles,  which  are  always  of  smaller  diameter 
than  the  middle  portion  to  permit  the  rolls  to  come  close  to- 
gether; and  (c)  the  portion  at  the  fillet  connecting  the  body 


PIG.  54.— Pair  of  rollers  by  Messrs.  Akrill  &  Co.,  Ltd.,  West 
Bromwich  for  rolling  rails.  AA,  bodies  of  the  rolls;  B,  B,  B,  B, 
necks  which  revolve  in  bearings  in  the  chocks;  C,  C,  C,  C,  wobblers, 
by  means  of  which  the  rolls  are  driven.  The  openings  between 
the  bodies  of  the  rolls  from  the  passes,  consisting  of  the  grooves 
a,  a,  bounded  on  each  side  by  a  collar,  b,  b,  and  closed  in  at  the  top 
by  the  closers  or  formers,  c,  c. 

and  the  necks,  called  the  shoulders.  Rolls  are  practically 
always  cast,  almost  never  forged  (steel  rolls),  to  rough  shape 
and  then  turned  down  to  the  exact  size.  On  account  of  the 
greater  hardness,  cast  iron  is  generally  employed  for  finishing 
a  piece;  if  cast  in  a  chill  (iron)  mold  to  make  the  surface  por- 
tion as  hard  and  smooth  as  possible  it  is  called  a  chill  (chilled) 
roll;  if  not  chilled,  a  grain  roll;  if  only  part  of  the  barrel  is  chilled, 
a  part  chill  roll.  Steel  rolls  are  always  cast  in  sand  without 
any  chilling  effect  and  are  subsequently  annealed  to  break  up 
the  coarse  crystallization  produced  by  slow  cooling.  They 
are  softer  than  cast  iron,  hence  are  sometimes  termed  soft 
rolls,  and  are  used  for  the  preliminary  working  or  roughing, 


404 


ROLLING 


or  where  a  very  smooth  surface  on  the  piece  is  not  required. 
If  the  barrel  is  perfectly  smooth,  as  for  the  production  of  plates, 
it  is  termed  a  plain  roll  or  flat  roll.  Where  material  of  uneven 
section  is  to  be  produced,  such  as  beams  or  angles,  the  rolls 
are  cast  with  depressions  or  grooves  and  raised  portions  or 
collars  to  correspond  (grooved  rolls).  A  half  roll  has  only 


FIG.  55. — Typical   American  housing. — (Harbord  and  Hall,  Met. 
of  Steel.) 

half  of  the  barrel  grooved;  this  is  generally  only  in  a  three-high 
mill  where  the  grooved  halves  of  the  top  and  the  bottom  roll 
are  at  opposite  ends,  the  whole  of  the  middle  roll  being  grooved. 
Hollow  rolls  are  those  (a)  which  have  a  hole  passing  through 
them  or  (b)  which  are  worn  or  turned  slightly  concave  in  the 
middle.  The  rolls  while  in  use  are  usually  sprayed  with  water 


ROLLING 


405 


to  prevent  them  from  becoming  overheated,  which  causes  cracks 
on  the  surface,  termed  water  cracks,  heat  cracks,  or  fire  cracks, 
as  these  produce  on  the  surface  of  the  piece  slight  elevations 
or  roll  marks  which,  in  the  case  of  small  sections,  may  become 
rolled  over,  giving  a  defect  called  a  lap.  Rolls  which  are  cracked 
to  any  extent  are  turned  smooth  (dressed)  in  a  lathe. 

A  pass  is  the  opening  between  a  pair  of  rolls  formed  by  cor- 
responding grooves  or  collars.  A  closed  pass,  box  pass,  or 
box  groove  is  formed  by  a  groove  in  one  roll  with  a  collar  on 
each  side,  and  fitting  into  this  opening  a  raised  portion  on 
the  other  roll  called  a  former  or  closer.  An  open  pass  con- 
sists of  a  groove  or  grooves  without  adjacent  collars.  A  blind 


FIG.  56. — Pinions  and  coupling  boxes. 

pass  or  false  pass  occurs  in  a  three-high  mill  where  there  is 
no  pass  in  the  top  (or  bottom)  roll  corresponding  to  the  groove 
in  the  bottom  (or  top)  roll  complementary  to  that  in  the  middle 
roll.  Passes  are  named  according  to  the  section  they  produce: 
gothic  pass  (like  a  double  gothic  arch);  diamond  pass;  oval 
pass;  convex  pass;  belly  pass  or  bellied  pass.  A  live  pass  is 
one  in  which  the  piece  is  worked,  and  a  dead  pass  is  the  reverse. 

Pass  is  also  the  term  used  for  the  travel  of  the  piece  of  metal 
being  worked,  once  between  the  rolls.  It  is  called  a  lost  pass 
in  the  case  of  a  two-high  non-reversing  mill  when  the  piece  is 
returned  to  the  original  side  over  the  top  roll,  during  which 
it  receives  no  work. 

The  housings  are  cast  of  cast  iron  or,  better,  for  heavy  work, 


406  ROLLING 

of  steel.  They  are  secured  to  massive  foundations  so  they 
will  be  perfectly  rigid.  They  kick  in  when  the  tops  incline 
toward  each  other.  Each  housing  looks  like  an  elongated 
letter  "U"  set  upright,  the  open  space  being  large  enough 
for  the  necks  of  the  rolls  resting  in  suitable  bearings  or  brasses, 
which  in  turn  are  held  in  place  by  chucks  or  chocks.  The 
chuck  on  the  top  of  a  lower  roll  which  supports  the  chuck  or 
bearing  of  the  roll  above  is  sometimes  termed  a  carrier.  The 
chuck  or  cap  over  the  top  roll,  against  which  the  housing  screw 
rests  to  keep  the  roll  in  the  desired  position  when  the  piece 
is  going  through,  is  called  the  rider.  In  a  two-high  mill,  when 
the  top  roll  is  adjusted  for  every  pass,  this  is  raised  by  rods 
resting  against  the  bearing  from  below  and  forced  up  by  a 
counterweight  hung  on  a  lever  arm  (balanced  roll),  or  by  hy- 


FIG.  57. — Pinions  and  spindles. 

draulic  means.  Across  the  top  of  the  housing  is  a  cap  (housing 
cap)  through  which  passes  the  housing  screw  or  pin  (Eng.) 
to  force  the  roll  down  and  keep  it  in  the  proper  position.  This 
screw  is  operated  by  a  hand  lever  (spanner)  for  three-high 
shape  or  bar  mills,  or  mechanically  for  two-high  mills  when  the 
top  roll  must  be  adjusted  for  each  pass.  In  the  latter  case 
the  distance  between  the  rolls  is  indicated  on  some  form  of 
gage.  Sometimes,  with  a  three-high  mill,  to  prevent  the  top 
roll  from  bending,  a  girder  or  bar  may  be  fastened  across  the 
tops  of  the  housings,  giving  the  middle  of  the  roll  an  additional 
bearing;  this  is  called  a  stiff ener.  A  set  of  rolls  and  the  housings 
which  hold  them  are  called  a  stand,  and  two  or  more  stands 
connected  together  constitute  a  train. 

One  end  of  each  roll,  or  both  if  there  is  more  than  one  stand 
in  the  mill,  is  given  a  cruciform  or  other  section  to  fit  a  corre- 


ROLLING  407 

spending  opening  in  the  coupling  box  by  which  it  is  connected 
with  the  spindle  in  a  similar  manner,  and  this  again  to  the  pinion 
and  the  engine.  The  end  of  a  roll  (or  spindle  or  pinion)  which 
has  this  section  is  called  the  wobbler  (or  wabbler).  The  spindles 
are  like  large  pieces  of  shafting  and  connect  the  rolls  with  the 
pinions,  or  the  rolls  in  one  stand  with  those  in  another;  they 
have  wobblers  on  the  ends  similar  to  those  on  the  rolls.  In 
some  cases  a  spindle  is  designed  to  break  if  the  piece  sticks  in 
the  rolls,  to  save  the  latter,  and  is  then  termed  a  breaking 
spindle.  The  pinions  are  gears  which  transmit  the  power  to 
the  rolls.  They  somewhat  resemble  short  rolls  with  teeth 
cast  on  the  barrel,  and  provided  at  the  ends  with  wobblers. 
The  pinions  are  also  supported  in  housings  (pinion  housings). 
The  jack  shaft  is  the  one  which  takes  the  power  from  the  engine 
shaft  and  transmits  it  by  the  pinions  and  the  spindles  to  the 
rolls.  In  some  cases  it  is  known  as  the  main  spindle  or  leading 
spindle.  The  manner  in  which  the  power  is  supplied  by  the 
engine  varies  according  to  the  size  and  the  type  of  mill.  If 
the  spindle  or  shaft  is  driven  directly  by  the  engine  shaft,  by 
means  of  a  casting  bolted  on,  known  as  a  crab,  the  mill  is  direct 
driven,  while  if  gears  are  interposed  either  to  reduce  or  in- 
crease the  speed  (almost  always  the  former),  it  is  gear  driven. 
With  small  mills  the  driving  may  be  done  by  a  belt  or  a  rope, 
and  these  are  belt  driven  and  rope  driven  respectively.  If  a 
motor  is  employed  the  mill  is  electrically  driven. 

If  small  sections  are  being  rolled  the  pieces  may  be  handled 
by  hand,  but  those'  which  are  too  heavy  are  supported  on  a 
series  of  rollers  on  each  side  of  the  rolls,  such  a  set  being  known 
as  a  table  or  roll  table.  If  these  are  not  driven  they  are  termed 
idle  rollers  or  idlers;  if  driven,  live  rollers;  if  one  of  the  latter 
becomes  broken,  a  dead  roller.  Underneath  the  rolls  a  pit 
is  usually  provided  to  catch  the  scale  which  comes  from  the 
piece,  and  called  a  scale  pit. 

The  piece  of  metal  being  rolled  is  usually  referred  to  as  the 
piece.  The  amount  by  which  it  is  reduced  in  section  for  a 
given  pass  is  palled  the  reduction  or  draft  (draught).  When 
the  piece  enters  the  rolls,  the  angle  determined  by  the  lines 
drawn  from  the  center  of  one  of  the  rolls  (a)  to  the  point  on 
the  circumference  which  the  piece  first  touches,  and  (6)  to 
the  center  of  the  other  roll,  is  called  the  entering  angle  or  angle 
of  contact,  and  must  in  general  be  less  than  30°  or  otherwise  the 
rolls  will  not  bite,  i.e.,  be  able  to  seize  the  piece  and  draw  it 
through.  To  assist  in  this,  a  little  sand  is  occasionally  put  on 
the  end  of  the  piece,  or  where  marks  on  the  surface  of  the  piece 
are  not  objectionable  the  rolls  are  chipped  out,  called  ragging, 
roughing,  or  cogging,  whereby  a  better  grip  is  obtainable. 
From  experiments  it  would  appear  that  the  rolls  exert  a  squirt- 
ing action  on  the  piece,  i.e.,  the  piece  on  leaving  the  rolls  is 
traveling  faster  than  the  circumference  of  the  rolls.  The  dif- 
ference in  rate  will  vary  with  the  thickness  of  the  piece,  the 
diameter  of  the  rolls,  and  the  amount  of  draft.  In  practice, 
in  arranging  the  successive  speeds  of  the  sets  of  rolls  in  a  tandem 


408  ROLLING 

continuous  mill  all  these  factors  must  be  taken  into  considera- 
tion. "If  there  are  four  such  stands  of  rolls,  each  effecting  a 
25%  reduction,  and  the  first  rolls  are  driven  at  64  revolutions 
per  minute  the  others  will  have  approximately  the  respective 
speeds  of  80,  100,  and  125.  Creeping  is  the  difference  in  rate 
between  different  parts  of  the  piece  passing  through  the  rolls. 
If  the  sides  of  the  piece  are  not  supported  by  grooves,  collars,  or 
supplementary  rolls  set  at  right  angles  to  the  others,  the  width  of 
the  piece  is  slightly  increased,  and  this  is  called  the  spread.  The 
extension  takes  place  in  the  direction  in  which  the  piece  is  travel- 
ing. If  the  rolls  are  horizontal  the  thickness  of  the  piece  will  be 
reduced,  while  the  width  will  be  slightly  increased;  with  vertical 
rolls,  the  width  will  be  reduced  and  the  thickness  somewhat 
increased.  Consequently,  if  both  the  thickness  and  the  width 
are  to  be  reduced,  it  will  be  necessary  either  to  (a)  turn  the 
piece  90°,  or  (b)  employ  both  horizontal  and  vertical  rolls.  In 
rolling  flat  material  it  is  usually  customary  to  give  it  one  pass 
vertically,  toward  the  end  of  tjie  operation,  to  insure  having 
the  width  right,  called  an  edging  pass.  The  operation  of 
rolling  a  piece  down  to  a  smaller  section  is  sometimes  termed 
(Eng.)  rolling  off  or  bolting. 

The  earliest  type  of  rolling  mill  consisted  of  two  plain  hori- 
zontal rolls  superimposed,  which  were  revolved  continuously 
in  one  direction,  hence,  when  the  piece  had  been  given  one 
pass,  and  before  it  could  be  given  another,  it  was  necessary  to 
bring  it  back  to  the  side  of  the  rolls  on  which  it  had  started. 
To  do  this  it  was  laid  on  top  of  the  top  roll,  and  so  carried  back, 
of  course  without  receiving  any  work.  This  type  is  called  a 
pull  over  or  pass  over  mill  and  is  still  employed  practically 
exclusively  in  the  sheet  and  tin  plate  industry.  George  Fritz 
improved  on  this  by  placing  a  third  roll  on  top  and  rotating 
it  in  the  same  direction  as  the  bottom  roll,  so  the  piece  would 
be  worked  between  the  top  and  the  middle  roll  on  the  way 
back.  This  is  called  a  three-high  mill  (rarely  a  Fritz  mill) 
and  the  former  type  a  two-high  mill;  German  designations  for 
them  are  respectively  trio  mill  and  duo  mill.  With  the  three-high 
mill,  since  the  ingot  or  piece  must  be  raised  or  lowered  for 
each  pass  an  amount  equal  to  the  diameter  of  the  middle  roll, 
the  tables  must  provide  .for  this  by  being  raised  or  lowered 
by  hydraulic  means  (lifting  table),  or  else  must  be  pivoted  in 
the  middle  and  arranged  with  gears  so  the  end  nearest  the  rolls 
can  be  sufficiently  raised  or  lowered  (tilting  table).  The  former 
type  is  generally  used  for  blooming  mills,  the  latter  for  plate 
and  shape  mills.  In  the  case  of  two-high  mills  the  tables  are 
stationary,  i.e.,  do  not  move  up  or  down. 

R.  M.  Daelen  devised  a  mill  with  both  vertical  and  hori- 
zontal rolls  so  that  all  four  sides  of  a  piece  could  be  rolled  in 
one  operation  without  the  necessity  for  turning  it  over,  and 
this  is  termed  a  universal  mill  (Daelen's  universal  mill).  Rams- 
bottom  built  a  mill  with  two  rolls  which  could  be  rotated  in 
either  direction,  thereby  avoiding  the  use  of  three  rolls  run 
continuously  in  one  direction.  This  is  called  a  reversing  mill 
(Ramsbottom's  reversing  mill),  the  other  a  non-reversing  mill. 


•  ROLLING  409 

The  first  grooved  rolls  were  introduced  by  Henry  Cort  (Cort's 
mill),  and  were  used  for  rolling  plain  rectangular  pieces,  but 
were  easily  modified  to  produce  various  irregular  sections. 
When  used  for  small  pieces  such  a  mill  is  called  a  bar  mill  or 
merchant  mill,  while  for  large  sections,  such  as  beams,  it  is 
known  as  a  shape  mill  (in  England,  a  section  mill).  In  this 
country,  bar  and  shape  mills  are  nearly  always  three-high,  or 
in  stands  of  two-high,  non-reversing,  on  the  continuous  or 
semi-continuous  principle  which  will  be  considered  later;  abroad 
they  are  frequently  two-high:  for  large  sections  reversing, 
and  for  small  sections  of  either  the  reversing  or  the  non-revers- 
ing type.  The  types  just  described  are  those  at  present  in  use, 
recent  improvements  consisting  in  the  arrangement  of  the  stands 
and  the  method  of  driving  the  rolls.  Thus  there  may  be  a 
number  of  stands  arranged  end  to  end,  called  a  train;  the  stands 
may  be  arranged  one  in  front  of  the  other  called  a  tandem 
continuous  mill;  or  there  may  be  several  combinations  of  the 
first  two.  There  are  also  several  patented  mills  which  will  be 
described  farther  on. 

CLASSIFICATION  OF  ROLLING  MILLS 

I.  Mills  which  depend  upon  the  arrangement  and  the 
rotation  of  the  rolls : 

1.  Two  horizontal  rolls:  two-high: 
(a)  Reversing: 

(i)  Top  roll  adjustable: 

Blooming,  cogging,  slabbing,  plate,  (for- 
eign), 
(ii)  Both  rolls  fixed: 

Shape. 

(&)  Non-reversing:  pullover: 
(i)  Top  roll  adjustable: 
Sheet  and  tin  plate. 
(ii)  Both  rolls  fixed: 

Merchant  mills  (foreign). 

2.  Three  horizontal  rolls :  three-high;  non-reversing: 

(a)  All  three  rolls  fixed: 
Shape,  merchant,  bar. 

(b)  Top  roll  adjustable,  middle  roll  movable: 
Plate  (Lauth) ;  blooming. 

3.  Universal  mill: 
(a)  Reversing: 

(i)  Two  horizontal  and  two  vertical  rolls: 
Slabbing;  plate;  shape  (Grey,  Sack,  etc.). 

(ii)  Two  horizontal  rolls    and  two  sets  of  ver- 
tical rolls  (two  each),  one  at  each  side  of 
the  horizontal  rolls: 
Plate. 
(6)  Non-reversing: 

Three  horizontal  rolls,  and  either  one  or  two 

sets  of  vertical  rolls  as  above: 

Plate. 


410  ROLLING  • 

II.  Mills  which  depend  upon  the  arrangement  of  the 
stands. 

1.  Two  or  more  stands  end  to  end  in  one  line:  train: 

(a)  Reversing,  two-high  (foreign) : 
Plate ;  shape. 

(b)  Non-reversing: 

(i)  Two-high: 

Sheet  and  tin  plate, 
(ii)  Three-high:  ' 

Shape ;  bar  or  merchant. 

2.  Two  or  more  stands  one  in  front  of  the  other: 
Two-high,  non-reversing: 

Continuous ;  Morgan  continuous ;  Bedson    con- 
tinuous. 

3.  Combinations  of  trains  and  continuous: 

(a)  Two  or  Inore  trains    usually  staggered:  there 
may  be  one  stand  alone,  but  all  rolls  are  of 
the  same  size: 

Shape;  rail;  merchant. 

(b)  One  train  of  small  rolls,  with  stand  of  larger 
rolls  in  front  for  roughing: 

Tandem  roughing  or  Belgian  (for    small  sec- 
tions). 

(c)  Two  or  more  stands  tandem,  and  one  or  more 
trains  staggered: 

Garrett  semi-continuous;  Morgan    semi-con- 
tinuous. 

III.  Mills  for  special' products,  or  in  which  there  is  no 
reduction : 

1.  No  reduction: 

(a)  Slitting  mills. 

(b)  Tube  mills  ( welded). 

2.  Reduction  or  change  of  form: 
(a)  Tire  and  wheel  mills. 

(6)  Mills  for  seamless  tubing: 
(i)  Piercing, 
(ii)  Rolling. 

IV.  Mills  based  upon  the  nature  of  their  product : 

1.  Semi-finished:  Roughing: 

Blooming;    billet;    cogging;    slabbing;    muck 
bar. 

2.  Finished:  Finishing: 

Shape;  plate;  rail;  bar  or  merchant;    hoop; 
cotton  tie ;  etc. 

The  size  or  rating  of  a  rolling  mill  for  everything  but  plates 
is  based  upon  the  pitch  diameter  of  the  rolls,  which  in  case  the 
rolls  are  of  exact  (nominal  size)  is  the  distance  between  their 
centers.  The  measurement,  however,  really  is  based  on  the 
distance  between  centers  of  the  pinions,  on  account  of  the  varia- 
tions in  the  size  of  rolls  due  to  turning  or  allowance  for  turning; 


ROLLING  411 

for  example,  a  30"  blooming  mill  or  a  16"  bar  mill.  In  the  case  of 
plate  mills  the  size  has  to  do  with  the  width  of  plate  which  can  be 
rolled,  which  in  turn  depends  upon  the  type  of  mill.  Thus  a  48  * 
universal  mill  (where  the  edges  are  rolled)  can  produce  finished 
plates  up  to  48"  wide;  a  140"  sheared  mill  indicates  that  the 
length  of  the  barrel  of  the  rolls  is  140",  but  on  account  of  the 
danger  to  the  mill  of  having  the  plate  project  beyond  this,  the 
extreme  width  as  rolled  will  be  about  three  or  four  inches  less  than 
this;  and  in  addition,  a  certain  allowance  (about  four  to  eight 
inches),  varying  with  the  thickness  and  the  length  of  the  plate, 
must  be  made  for  side  shearing. 

Product. — In  using  large  ingots,  or  where  the  product  is 
very  small  in  size,  it  is  generally  the  practice  to  roll  down  par- 
tially on  one  mill,  and  finish  on  another.  These  two  classes 
are  termed  respectively  semi-finished  products  (semi-products) 
and  finished  products.  Semi-finished  products  are  divided 
into  (i)  blooms  and  billets,  the  names  being  more  or  less  inter- 
changeable, both  being  rectangular  in  cross-section,  and  square 
or  nearly  so;  in  general  billets  are  considered  as  having  a  cross- 
section  of  from  4  up  to  36  square  inches,  the  width  never  being 
equal  to  twice  the  thickness;  smaller  sizes  are  usually  classed 
as  bars,  but  in  certain  cases  are  termed  small  billets;  blooms 
is  the  name  applied  when  the  cross-section  is  greater  than  36  square 
inches.  (2)  Slabs  are  rectangular  pieces  to  be  rolled  down  into 
plates  (they  may  be  considered  as  very  heavy  plates),  where  the 
width  is  at  least  equal  to  twice  the  thickness.  (3)  Sheet  bars  or 
tin  bars  are  small  slabs  used  for  making  sheets  and  tin  plates;  if 
made  of  charcoal  wrought  iron  they  are  termed  charcoal  bars; 
ordinary  sheet  bars  are  called  coke  bars. 

Mills  for  semi-finished  products. — Billets,  blooms,  small 
slabs,  and  sheet  bars  are  produced  oh  a  mill  called  a  billet 
mill,  blooming  mill,  or  cogging  mill.  The  first  two  names  are 
used  in  this  country,  more  particularly  where  the  product 
is  not  used  directly  in  some  finishing  mill,  the  last  name  being 
sometimes  used  to  cover  this  case;  in  England  cogging  mill  is 
used  for  all.  The  ordinary  style  of  mill  consists  of  one  stand 
of  rolls,  either  two-high  or  three-high,  about  30"  to  40"  in  diam- 
eter. The  rolls  are  divided  into  passes  of  different  widths  by 
collars,  and  are  usually  ragged,  at  least  for  the  first  few  passes; 
they  are  called  blooming  rolls  or  billeting  rolls.  The  ingots 
used  generally  weigh  from  about  4000  up  to  8000  Ibs.  or  over, 
and,  as  it  is  necessary  to  turn  them  90°  after  every  few  passes, 
a  mechanical  device  must  be  employed  which  is  called  a  manip- 
ulator (rarely  a  tilter).  With  a  three-high  mill  it  usually 
consists  of  a  framework  mounted  on  wheels  so  it  can  be  moved 
backward  and  forward  under  the  roll  table.  It  has  vertical 
projections  called  fingers  or  tappets  which,  by  lowering  the 
table,  will  pass  up  between  the  rollers  and  catch  the  ingot  near 
the  edge  and  thereby  force  it  over.  By  lowering  the  table 
sufficiently  the  ingot  will  rest  on  the  carriage,  between  the 
fingers,  which  can  then  be  moved  so  as  to  bring  the  piece  in 
front  of  the  pass  it  is  to  enter.  In  the  case  of  a  two-high  mill, 


412  ROLLING 

where  the  tables  are  stationary,  the  manipulator  must  be  capa- 
ble of  movement  in  a  vertical  as  well  as  a  horizontal  direction; 
by  certain  arrangements  vertical  movement  may  not  be  neces- 
sary. Turning  a  billet  over  90°  for  the  last  pass  to  remove 
any  fin  is  sometimes  called  curing  (Eng.).  A  piece  which  twists 
on  its  axis  when  entering  the  rolls  is  sometimes  said  to  turn 
down;  as  a  result  the  piece  is  not  a  true  rectangle  in  cross- 
section  and  is  said  to  be  rolled  diamond. 

Another  type  of  mill  for  small  billets  and  sheet  bars  is  the 
continuous  mill  with  rolls  about  12"  to  16"  in  diameter.  This 
consists  of  a  number  of  stands  of  two-high,  non-reversing  rolls, 
one  behind  the  other,  which  are  driven  at  progressively  increas- 
ing speeds.  In  some  arrangements,  the  last  or  finishing  stand, 
placed  at  a  little  distance  from  the  others,  is  called  the  bull 


FIG.  58. — Shape  roll  (top)  blooming  roll  (bottom). 

head.  To  work  all  sides  of  the  piece  one  of  two  arrangements 
is  necessary:  in  the  Bedson  continuous  mill  the  rolls  in  succes- 
sive stands  are  alternately  horizontal  and  vertical,  or  else  set 
at  an  angle  of  45°  alternately  to  the  right  and  the  left.  In 
the  Morgan  continuous  mill  all  the  rolls  are  horizontal,  and 
the  piece  is  turned  or  twisted  by  special  guides  (twisted  guides) 
which  look  something  like  a  bell  open  at  both  ends,  and  with 
a  spiral  or  angular  groove  cut  in  them. 

With  the  ordinary  type  of  blooming  mill  first  described  the 
ingot  is  rolled  out  into  one  piece  which  is  subsequently  cut  up 
by  shears,  consisting  of  two  knife  blades,  one  fixed  and  one 
movable,  the  latter  actuated  by  gearing  from  a  steam  engine 
(steam  shears)  or  motor  (electric  shears),  or  by  a  hydraulic 
cylinder  (hydraulic  shears);  if  the  blades  are  set  at  a  slight 
angle  (rake)  to  each  other  it  is  termed  a  guillotine  shears.  In 


ROLLING  413 

the  case  of  continuous  billet  mills  the  lengths  obtained  are  so 
great  that  the  length  of  the  tables  would  be  excessive  if  the 
shearing  were  not  done  until  the  entire  piece  had  been  rolled. 
Hence  a  special  type  of  shears  has  been  devised  (Edwards' 
flying  shears).  This  cuts  the  piece  while  it  is  issuing  from  the 
last  stand,  and  is  operated  by  two  steam  cylinders,  one  of  which 
brings  the  knife  down  on  the  piece,  while  the  other,  immediately 
afterward,  throws  the  knife  outward  so  it  will  not  interfere  with 
the  progress  of  the  remainder.  It  is  operated  by  a  trigger  which 
is  set  for  the  desired  length,  and  is  sprung  by  the  piece  itself 
striking  it. 

Slabbing  mills  may  be  considered  as  heavy  plate  mills,  and 
are  usually  of  the  two-high,  universal  type,  sometimes  pro- 
vided with  a  manipulator  for  turning  the  ingot.  The  rolls 
are  about  30"  in  diameter  and  are  smooth  (without  any  ragging) 
as  all  precautions  must  be  taken  to  prevent  scale  from  being 
rolled  into  the  surface  of  the  piece,  as  this  would  cause  a  bad 
surface  on  the  finished  plate.  Muck  mills  are  the  mills  used 
in  connection  with  puddling  for  rolling  the  puddle  balls,  after 
squeezing,  into  rough  bars  (muck  bars).  They  are  usually 
three-high  (rarely  two-high,  pull  over)  with  rolls  from  about 
1 8"  to  24"  in  diameter. 

Mills  for  finished  products. — These  may  be  divided  into 
plate  mills  and  shape  mills,  for  large  sections,  and  bar  mills 
or  merchant  mills  for  small  sections.  On  them  slabs,  billets, 
or  blooms  are  rolled  down  into  finished  material.  The  term 
merchant  mill  was  first  used  in  connection  with  the  manufac- 
ture of  wrought  iron  to  distinguish  the  mill  or  train  on  which 
the  material  was  finished  ready  for  sale  from  the  muck  train 
or  forge  train  (forge  rolls  or  puddle  train)  which  rolled  the 
puddle  balls  after  squeezing  or  shingling  into  muck-bar:  the 
term  has  been  retained  to  designate  a  mill  on  which  small  sections 
are  rolled. 

Plate  mills  are  divided  into  sheared  plate  mills  where  the 
edges  are  not  rolled  and  must  be  sheared  off  (side  shears); 
and  universal  mills  where  the  edges  are  rolled  and  hence  only 
the  ends  need  be  cut  (end  shears).  The  size  of  sheared  mills 
is  about  60"  to  200",  and  of  universal  mills,  about  18"  to  48". 
The  universal  mills  are  nearly  all  two-high,  reversing,  with 
two  sets  of  vertical  rolls,  one  on  each  side  of  the  horizontal 
rolls.  They  may  roll  slabs  or  slab  ingots  (wide  flat  ingots). 
In  this  country  and  on  the  Continent,  nearly  all  the  sheared 
mills  are  three-high,  non-reversing,  but  in  England  the  prefer- 
ence is  for  two  stands  of  two-high,  reversing  rolls,  one  stand 
for  roughing  and  the  other  for  finishing;  slabs  are  generally 
rolled.  The  barrels  of  the  rolls  are  smooth,  and  as  soon  as 
they  become  rough  must  be  dressed  (turned  down) .  In  Germany 
there  is  a  modification  where  the  rolls  have  collars  for  producing 
plates  of  narrow  width,  very  similar  to  the  bar  mills  used 
elsewhere  for  the  purpose.  With  universal  mills  the  slab  or  ingot 
is  rolled  back  and  forth  until  the  desired  gage  (thickness  and 
width)  is  obtained.  With  sheared  mills  this  practice  may  be  fol- 


414  ROLLING 

lowed  or  else,  with  narrow  slabs,  the  rolling  may  proceed  until  the 
length  of  the  slab  has  been  increased  sufficiently  for  the  width  of  the 
plate,  when  it  is  swung  around  90°  by  hooks  suspended  from  over- 
head beams.  In  the  first  case  the  plate  is  said  to  be  rolled 
longitudinally,  in  the  second  case,  transversely  (in  England  called 
spreading  and  turning).  Rolling  transversely,  particularly  semi- 
finished material,  is  also  called  cross  rolling.  It  is  claimed  to 
effect  almost  complete  elimination  of  seams  and  surface  defects 
in  the  case  of  billets  or  slabs.  The  type  of  three-high  mill  used 
in  this  country  is  called  the  Lauth  mill,  the  special  feature  being 
the  middle  roll  which  is  about  two-thirds  the  diameter  of  the 
other  rolls.  This  smaller  roll  gives  greater  kneading  action  to  the 
piece.  The  bottom  roll  is  fixed  in  its  bearings,  but  the  height  of 
the  top  roll  is  adjustable  by  means  of  the  housing  screws  which 
are  regulated  by  a  man  called  the  screw  down.  The  middle 
roll  rests  against  either  the  top  or  the  bottom  roll  to  stiffen 
it,  depending  upon  the  direction  in  which  the  piece  is  traveling. 
There  is  bound  to  be  a  certain  amount  of  spring  in  the  rolls,  even 
when  supported,  particularly  when  rolling  wide  plates  and  this 
together  with  the  greater  wear  or  channeling  of  this  portion  of  the 
rolls  causes  the  plates  to  be  thicker  in  the  middle  than  at  the 
edges;  the  amount  above  the  theoretical  or  normal  thickness  is 
known  as  the  crown  of  the  plate.  After  rolling,  the  plates  are 
made  flat  by  passing  through  straightening  rolls  which  consist  of 
a  series  of  upper  and  lower  rolls  staggered.  The  tables  on  which 
the  plates  are  taken  to  the  shears  and  allowed  to  cool  are  called 
cooling  tables,  cooling  beds,  or  hot  beds. 

Shape  mills. — In  this  country  they  are  usually  composed 
of  several  stands  of  three-high  rolls  in  one  or  more  trains.  The 
first  stand  is  called  the  roughing  stand  or  roughing  rolls  (rarely 
roughing  rollers,  rough  rollers,  breaking  down  rolls,  bolting 
down  rolls),  the  last,  the  finishing  stand  or  finishing  rolls, 
and  those  between,  strand  rolls.  The  problem  of  designing 
the  successive  passes  in  the  rolls  to  produce  the  desired  section 
is  one  requiring  great  experience  and  skill.  In  rolling  sections, 
such  as  beams  and  channels,  on  an  ordinary  three-high  mill, 
since  different  parts  of  the  rolls  have  different  diameters  corre- 
sponding to  the  section,  there  is  always  a  certain  amount  of 
tearing  action  going  on  which  appears  to  effect  horizontal 
as  well  as  vertical  reduction,  but  is  not  true  rolling.  The 
smaller  parts  of  the  section  which  have  to  be  as  long  as  the 
larger  ones  are  said  to  be  drawn.  To  reduce  this  tearing  action 
as  far  as  possible,  and  more  particularly  to  provide  clearance 
for  the  rolls,  the  flanges  of  a  channel,  beam,  etc.,  must  be  tapered. 
With  ordinary  methods  the  flanges  cannot  be  very  high  as  the 
deep  grooves  required  would  make  the  rolls  too  weak,  and  also  the 
metal  would  become  too  cold  to  penetrate  to  the  bottom  or,  as  it 
is  commonly  expressed,  the  section  would  not  be  filled  out. 
Adjusting  the  rolls  to  produce  a  section  of  the  proper  gage  and 
weight  is  called  lining  the  rolls;  when  a  heavier  section  is  required 
the  rolls  must  be  separatd  slightly  (lining  up),  and  thin  metal 
strips  (liners)  are  inserted  between  the  bearing  blocks;  for  lighter 


ROLLING  415 

sections  the  rolls  are  lined  down  by  removing  one  or  more  of  these 
strips. 

Guides  and  guards. — To  avoid  delays  in  inserting  the  piece 
in  the  right  pass,  two  pieces  of  metal,  called  guides,  are  fastened, 
one  on  each  side  of  the  pass  on  the  entering  side  of  the  rolls, 
to  rods  extending  across  the  rolls.  These  pieces  diverge  at 
their  outer  ends  so  it  will  be  easy  to  introduce  the  piece,  the 
inner  ends  which  nearly  touch  the  rolls  converging  so  the  distance 
between  them  is  the  same  as  the  width  of  the  pass.  Particularly 
in  rolling  shapes,  the  piece,  instead  of  coming  out  flat,  may  stick 
to  one  of  the  rolls  and  become  wrapped  around  it,  an  action 
known  as  collaring.  Any  piece  which  does  this,  or  has  become  so 
bent  or  twisted  it  cannot  be  finished,  is  termed  a  cobble.  To 
prevent  this  as  far  as  possible  guards  or  stripping  plates  are  placed 
at  the  top  and  the  bottom  of  a  pass  on  the  issuing  side;  the  inner 
side  is  tapered  and  rests  on  the  rolls.  The  bottom  guard  is 
usually  bolted  to  a  rod  running  across  the  rolls  while  the  top  one 
is  hung  on  a  similar  rod  and  held  in  place  by  a  counterweight, 
and  is  called  a  hanging  guard  (rarely  a  yielding  guard  or  clearer). 
In  connection  with  the  roughing  rolls  for  muck  bar,  pieces  called 
scrapers  are  sometimes  employed,  which  are  similar  to  guards, 
but  placed  slightly  above,  to  scrape  off  any  pieces  of  iron  which 
fall  from  the  bloom  or  which  stick  to  the  roll. 

Bar  mills,  also  called  merchant  mills  or,  on  account  of  the 
special  product  which  they  make  (but  to  which  they  are  not 
necessarily  restricted),  rod  mill,  hoop  mill  or  strip  mill,  cotton 
lie  mill.  As  a  rule  they  are  of  the  three-high,  non-reversing, 
or  of  the  two-high,  continuous  type,  and  the  sections  rolled 
rarely  exceed  3"  square.  The  simplest  type  is  where  there  are 
a  number  of  stands  in  train,  all  the  rolls  being  of  the  same  size. 
With  six  such  stands  they  are  designated  as  follows: 

ist  stand  (three-high)  roughing  stand  (roughing  rolls). 

2d       "  "  pony  roughing  stand. 

3d       "  first  strand. 

4th  second  strand. 

5th      "     (two-  or  three-high)  planishing  rolls. 

6th  finishing  stand  or  chilled  rolls. 

The  side  of  the  mill  on  which  the  piece  first  enters  is  some- 
times called  the  roller's  side,  and  the  opposite,  the  catcher's 
side;  these  terms  are  generally  restricted  to  pull  over  mills, 
such  as  those  described  under  Sheets  and  Tin  Plate.  Fore 
plate  is  the  name  sometimes  applied  to  a  plate  at  the  bottom 
of  and  connecting  the  two  housings;. it  is  supported  by  cramp 
bars  to  which  the  guides  and  guards  are  fastened.  Rests 
are  pieces  placed  before  the  rolls  and  just  below  the  top  of 
the  lower  roll  upon  which  the  bloom  or  bar  may  be  rested  while 
being  pushed  into  the  rolls.  A  feed  roll  is  a  small  driven  roll 
sometimes  placed  immediately  in  front  of  a  stand  of  rolls  to 
facilitate  the  introduction  of  the  piece.  Pinch  rolls  are  for  the 
same  purpose  as  the  preceding,  and  consist  of  two  small  driven 


41 6  ROLLING 

rolls  which  grip  the  piece  just  tightly  enough  to  carry  it  into  the 
rolls. 

To  increase  the  speed  of  rolling  and  so  permit  greater  lengths 
to  be  rolled,  instead  of  simply  passing  the  piece  backward 
and  forward  through  the  rolls  (i.e.,  the  end  which  is  the  first  to 
enter  the  rolls  on  one  pass  is  the  last  to  enter  on  the  next), 
when  the  piece  is  sufficiently  reduced  in  section  the  end  issuing 
from  the  rolls  may  be  bent  around  and  inserted  immediately 
in  the  next  pass  (looping),  and  in  this  way  a  piece  may  be  in 
two  or  three  passes  at  the  same  time;  where  this  is  done  the 
mill  is  called  a  looping  mill.  With  the  smaller  pieces  it  is  neces- 
sary to  enter  them  by  hand,  but  with  those  of  intermediate 
or  larger  size  labor-saving  devices  known  as  repeaters  or  turn- 
overs are  frequently "  employed.  With  the  intermediate  sec- 
tions these  consist  of  a  vertical  curved  guide  with  a  driven 
roller  at  some  distance  from  the  rolls  which  serves  to  bring 
the  end  around  and  return  it  to  the  rolls  for  the  next  pass;  in 
the  Morgan  semi-continuous  mill  (also  called  a  repeating  mill) 

-  this  is  effected  by  curved  grooves  cast  in  the  heavy  iron  plates 
forming  the  floor  or  bed  of  the  mill. 

Hand  mill  and  guide  mill. — These  are  the  two  forms  of  an 
ordinary  bar  mill.  In  both  the  piece  is  handled  by  men  with 
tongs.  In  the  case  of  the  hand  mill  for  the  last  pass  the  piece 
must  be  entered  in  the  right  position  and,  if  necessary,  held 
with  the  tongs  to  prevent  it  from  turning,  and,  when  rolling 
rounds,  the  piece  must  be  put  through  the  last  pass  about  three 
times,  being  turned  each  time  90°  to  insure  a  true  section.  In 
a  guide  mill,  which  is  generally  of  small  size,  at  least  the  last 
pass  is  provided  with  a  closed  guide.  This  is  a  bell-shaped 
tube,  the  outward  end,  into  which  the  end  of  the  piece  is  thrust, 
having  a  pronounced  flare,  and  the  other  end,  which  is  as  close 
to  the  rolls  as  possible,  having  a  hole  just  the  shape  of  the  piece 
in  order  to  hold  it  in  the  right  position  and  prevent  it  from 
turning  or  twisting  when  gripped  by  the  rolls.  This  second 
type  of  mill  requires  only  one  pass  through  the  finishing  pass, 
and  is  very  generally  used  for  rolling  small  sections  such  as  hoop, 
etc.,  where  the  speed  of  the  rolls  is  great.  In  certain  districts 
a  mill  operated  by  hand  without  closed  guides  is  called  a  hand 
guide  mill.  A  guide  roll  (Eng.)  is  the  smallest  size  used  in  an 
iron  works,  and  is  employed  in  the  production  of  the  smallest 
sections  which  are  only  one  size  thicker  than  wire  rods  (Turner). 

To  enable  the  finishing  rolls  to  be  driven  at  a  higher  speed 
than  the  roughing,  and  also  to  be  able  to  handle  a  larger  billet, 

•  one  stand  of  roughing  rolls  of  larger  diameter,  driven  independ- 
ently, is  sometimes  placed  in  front  of  and  ,a  short  distance  away 
from  the  first  stand  of  the  regular  train.     This  arrangement 
is  termed  a  Belgian  mill  or  a  tandem  roughing  mill. 

The  AlUs-Andrew  process  for  rolling  very  thin  sheets  or 
strips  consists  in  coating  a  number  of  strips  with  a  composition 
to  prevent  them  from  sticking,  and  riveting  them  together  at 
one  end.  They  are  then  heated  and  rolled  down  on  the  principle 
of  a  pack  of  tin  plates.  » '* 


ROLLING  417 

G.  Balthasar's  universal  mill  for  rolling  bars  consists  of  a 
pair  of  horizontal  and  a  pair  of  vertical  rolls  so  arranged  that 
any  groove  of  the  horizontal  rolls  may  be  brought  into  position 
with  a  similar  groove  in  the  vertical  rolls. 

The  Belgian  wire  rod  mill  is  one  in  which  the  stands  of  rolls 
are  placed  in  train,  i.e.,  end  to  end;  the  modification  where 
the  piece  was  first  subjected  to  a  preliminary  rolling  in  an  in- 
dependent stand  constitutes  the  German  mill,  although  this 
is  now  generally  called  a  Belgian  mill. 

The  Bickley  mill  for  hoop  and  cotton  ties  consist  of  three- 
high  rolls  through  which  the  piece  is  passed  by  repeaters,  and 
provided  with  devices  for  taking  care  of  the  slack,  followed  .by 
a  number  of  two-high  finishing  stands. 

J.  J.  Bleckley's  four -high  mill  for  wire  rods  consists  of  two 
sets  of  rolls  one  above  the  other  in  the  same  housing  with  a 
repeater  for  bending  down  the  piece  from  the  upper  to  the 
lower  set;  a  number  of  such  stands  could  be  provided,  driven 
at  progressively  increasing  speeds. 

The  Boecker  mill  is  somewhat  similar  to  the  Belgian  mill, 
having  two  lines  of  stands  two-high,  one  on  each  side  of  a  driving 
shaft. 

Brown's  reciprocating  mill  has  two  pairs  of  rolls  in  one  set 
of  housings  on  the  same  level,  the  two  pairs  being  run  in  oppo- 
site directions.  Alternately  in  each  pair  the  passes  are  con- 
siderably larger  than  in  the  other,  the  piece  being  rolled  in 
the  small  passes  and  passing  through  the  large  passes  without 
touching  them.  The  object  is  to  run  the  rolls  without  revers- 
ing and  to  avoid  the  necessity  for  a  lifting  table. 

Brownhill  and  Smith's  mill  is  three-high  with  the  middle 
roll  slightly  larger  than  the  bottom,  and  the  top  roll  slightly 
larger  than  this. 

In  Bunsen's  mill  for  rolling  hoop  there  are  three  pairs  of 
rolls  arranged  one  behind  the  other,  the  first  and  the  third 
set  having  grooves  cut  in  the  bottom  roll,  and  the  middle  set 
a  groove  cut  in  the  top  roll. 

The  Dowlais  mill  consists  of  two  pairs  of  rolls  in  one  set  of 
housings,  the  bottom  roll  of  one  set  being  on  a  level  with  the 
top  roll  of  the  other  set,  the  two  pairs  being  run  in  opposite 
directions.  The  advantage  claimed  is  that  there  are  no  dead 
passes  as  with  an  ordinary  three-high  mill. 

In  the  Garrett  semi-continuous  mill,  used  principally  for 
rolling  wire  rods,  there  are  a  number  of  stands  placed  one  behind 
the  other,  following  which  are  a  number  of  trains  of  two  or 
three  stands  each,  and  driven  at  successively  increasing  speeds, 
the  piece  being  louped  around  by  trough  guides  in  the  floor,  and 
arranged  so  that  from  two  to  four  pieces  can  be  finished  at  the 
same  time. 

Gillon  and  Dujardin's  mill  is  about  the  same  as  Lauth's  three- 
high  mill. 

The  Grey  universal  mill  is  designed  principally  for  rolling 
beams  with  deeper  and  thinner  flanges  than  are  possible  on  an 
ordinary  shape  mill.  The  ingots  are  first  rolled  into  shaped 
27 


4i  8  ROLLING 

blooms  (the  section  roughly  started)  on-  an  ordinary  cogging 
or  blooming  mill,  which  are  then  taken  to  the  Grey  mill.  This 
consists  of  two  stands,  the  first  of  which  contains  one  pair  of 
horizontal  rolls  only.  In  these  only  the  edges  of  the  flanges 
are  rolled,  i.e.,  the  bloom  is  rolled  down  to  a  thickness  corre- 
sponding to  the  depth  (width)  of  the  flanges  required.  The 
second  stand  has  one  pair  of  horizontal  rolls  and  one  pair  of 
vertical  rolls  arranged  so  they  both  act  on  the  piece  simul- 
taneously, the  horizontal  rolls  being  power  driven,  while  the 
vertical  rolls  are  friction  driven  (i.e.,  from  the  pressure  of  the 
piece  against  them).  The  section  is  guided  through  the  rolls 
by  laterally  adjustable  guide-bars,  and  is  supported  under- 
neath by  guide-rollers.  It  is  never  lifted  or  turned,  but  passes 
backward  and  forward  until  finished.  The  horizontal  rolls 
must  be  changed  to  conform  to  the  depth  of  the  section,  but 
the  vertical  rolls  which  work  the  outer  surfaces  of  the  flanges 
are  wide  enough  for  all  sections  and  therefore  need  not  be  changed 
except  when  they  become  badly  worn. 

The  Josserand  and  Jacquet  process  is  for  rolling  bright  steel 
bars.  The  bars  are  turned  and  then  rolled  to  within  between 
o.oi"  and  0.05  "of  the  finished  size.  Special  finishing  machines 
consist  of  six  stands  tandem,  on  a  common  bed  plate  but  driven 
independently:  (i)  straightening,  (2)  pulling  through,  (3) 
roughing  cut,  (4)  pulling  through,  (5)  finishing  cut,  and  (6) 
planishing  (/.  /.  &•  S.,  1915,  i,  591). 

The  Kirkstall  process  for  producing  rods  which  are  very 
straight  and  accurate  as  to  gage  consists  in  taking  bars  rolled 
in  the  ordinary  manner  to  a  diameter  slightly  larger  than  desired, 
and  then  finishing  them  at  a  dull  red  heat  between  two  disks 
which  are  parallel  to  each  other  and  revolve  in  the  same  direction, 
but  with  their  horizontal  axes  not  in  the  same  plane. 

The  Kloman  process  for  making  eye  bars  consisted  in  rolling 
the  billets  between  reversible  and  adjustable  rolls  in  such  a 
manner  as  to  leave  the  ends  of  the  bar  thicker  than  the  body. 
The  ends  were  then  spread  and  forged*  and  the  eye  punched 
out  under  a  steam  hammer. 

F.  Kogel's  universal  mill  is  designed  to  produce  a  variety 
of  sections  difficult  to  roll  on  an  ordinary  mill  by  a  combina- 
tion of  various  processes  in  some  of  which  the  piece  is  acted 
upon  by  rolls  without  getting  any  forward  movement;  it  was 
apparently  intended  principally  for  wrought  iron. 

The  Lackawanna  or  Mathias  deseaming  process  was  devised 
principally  for  the  purpose  of  removing  the  seamy  portion  of 
billets  entering  into  the  manufacture  of  rails.  "The  machine  by 
which  the  metal  is  removed  subjects  the  hot  rail  bar  on  the  top  and 
bottom  surfaces  to  the  cutting  action  from  the  teeth  on  two 
opposed  rotating  saw  disks,  just  after  the  hot  bar  comes  down  the 
mill  table  from  the  last  roughing  pass.  During  this  stage  of 
travel  a  collar  turns  the  rail  bar  so  that  its  head  is  down  and  the 
base  up.  The  bar  then  enters  a  tunnel  about  20  feet  long  and 
lined  with  fire-brick  to  check  heat  radiation.  It  is  then  forced 
between  the  saw  disks  by  a  pair  of  driven  pinch  rolls,  adjustable 


ROLLING  419 

to  bars  of  various  sizes  and  having  guides  for  the  top,  bottom  and 
sides  of  the  bar.  Adjustment  of  the  saws  is  made  for  a  cut  }^' 
or  at  the  extreme  %  §"  deep.  A  second  set  of  driven  pinch  rolls, 
on  the  delivery  side,  helps  to  force  the  bar  against  the  cut  of  the 
saw  teeth  and  similarly  a  second  set  of  guides  here  helps  to  hold  the 
bars  rigidly  and  firmly  during  the  passage  through  the  saw. 
From  the  delivery  set  of  pinch  rolls  the  bar  travels  through 
about  40  feet  more  of  tunnel  similar  to  that  on  the  entering  side 
and  then  to  the  finishing  stand.  The  hot  bar  enters  the  saw  at  a 
speed  of  about  350  feet  per  minute,  is  slowed  down  by  the  cutting 
operation  to  about  79  feet  per  minute,  and  on  leaving  the  saw 
rapidly  picks  up  speed  and  enters  the  finishing  stand  at  about 
500  feet  per  minute.  The  upper  saw  disk  (operating  on  the  base) 
has  an  8"  and  the  lower  a  6"  face.  Both  are  driven  from  belted 
motors,  are  5  feet  in  diameter,  and  run  at  a  peripheral  speed  of 
25,000  feet  per  minute  or  both  disks  together  make  800,000  tooth 
contacts  with  the  bar  per  minute.  The  rail  bars  after  passing 
through  the  machine  are  further  reduced  in  the  rolling  operation 
in  5,  more  or  less,  passes  to  the  finished  section,  so  the  rail  has  a 
rolled  surface  after  the  defective  material  has  been  removed 
"(pamphlet,  Lackawanna  Steel  Co.,  1914)." 

In  S.  McCloud's  process  for  rolling  old  steel  rails  into  flat 
plates,  heavy  steel  rails  are  cut  into  short  lengths,  heated  in 
the  ordinary  manner,  and  then  passed  endwise  through  a  set 
of  specially  prepared  rolls  which  gradually  flatten  both  the  head 
and  the  flange  of  the  rail  without  permitting  any  folding,  as 
the  steel  would  not  weld. 

E.  W.  McKenna's  process  for  rerolling  old  rails  into  lighter 
sections  (of  rails)  is  to  take  the  worn  rails,  heat  them  in  long 
furnaces,  and  give  them,  while  at  a  comparatively  low  tem- 
perature, two  passes  in  a  tandem  mill.  The  reduction  varies 
with  the  condition  of  the  worn  section,  but  as  a  rule  gives  a 
rail  of  about  from  10  to  12%  lighter  weight  then  the  original 
section  (R.  W.  Hunt). 

The  Morgan  semi-continuous  mill  for  bars  is  somewhat 
similar  to  the  Garrett  mill,  having  a  number  of  stands  of  rolls 
one  behind  the  other,  and  then  one  train  of  rolls  through  which 
the  piece  is  louped  by  trough  guides  in  the  floor. 

A.  Reese's  universal  mill  for  beams  and  channels  consists 
of  two  sets  of  rolls;  in  the  first  or  roughing  set  the  web  is  rolled 
by  horizontal  rolls,  and  at  the  same  time  the  width  of  the  flanges 
is  regulated  by  collars  on  a  pair  of  vertical  rolls;  the  finishing 
is  done  in  the  second  set  where  the  outer  sides  of  the  flanges 
are  rolled  and  the  shape  finished.  It  may  also  be  used  for 
plates. 

Rerolling  is  the  term  applied  to  the  operation  of  rolling  worn 
out  material  into  something  else;  it  is  used  principally  for  old 
rails.  Rails  which  are  to  be  rerolled  into  bars  and  angles  are 
usually  first  split  longitudinally  by  putting  them  through  a 
pass  (slitting  pass)  with  collars  which  slightly  overlap  and 
act  as  a  shear,  whereby  they  are  divided  into  three  pieces: 
the  head,  the  web,  and  the  flange.  The  first  is  used  for  rolling 


420  ROLLING— ROLLING  MILLS 

into  bars,  and  the  two  last  for  angles  and  flats.  A  mill  for 
cutting  up  nail  plate  in  this  manner  is  called  a  slitting  mill, 
and  no  reduction  is  effected. 

The  Sack  universal  mill,  designed  principally  for  rolling 
cruciform  sections,  has  horizontal  and  vertical  rolls  which  act 
upon  the  piece  simultaneously,  the  general  arrangement  being 
much  like  that  of  the  Wenstrom  mill. 

Slick's  angular  method  of  rolling  (patented  by  E.  E.  Slick), 
which  allows  shapes  with  wide  flanges  to  be  rolled  on  ordinary 
mills  other  than  universal  mills  having  horizontal  and  vertical 
rolls,  consists  in  so  designing  the  passes  that  one  flange  in  the 
case  of  a  channel,  or  alternate  (diagonally  opposite)  flanges 
in  the  case  of  a  beam,  are  rolled  at  an  angle  considerably  greater 
than  90°  to  the  web,  the  other  flange  or  flanges  going  through 
a  dead  pass  (i.e.,  not  worked),  the  action  being  reversed  on 
the  subsequent  pass.  In  this  way  the  sides  of  the  flanges  receive 
a  considerable  amount  of  work,  which  is  not  the  case  with  the 
ordinary  method  of  rolling.  After,  the  various  parts  of  the 
section  have  been  reduced  to  the  desired  thickness  the  flanges  are 
bent  into  their  final  position  in  a  series  of  passes'.  In  all  the 
reducing  passes  the  web  is  at  an  angle  to  the  axis  of  the  rolls, 
this  angle  being  reversed  in  successive  passes.  The  web  is 
also  supported  during  the  passes  in  which  the  flanges  are  bent 
into  their  final  position.  The  bending  of  the  flanged  shape 
in  passes  which  support  the  web  is  also  of  importance,  as  this 
prevents  distortion  of  the  web  and  insures  a  good  product.  In 
all  passes  there  is  no  turning  of  the  blank  to  a  position  at  right 
angles  to  that  in  the  previous  pass. 

D.  Turk's  system  of  rolling  wire  rods  consists  of  special  means 
of  automatically  bringing  oval  or  square  rods  from  one  pass 
to  another. 

E.  D.  Wassell's  process  consists  in  rerolling  old  steel  rails 
by  the  use  of  rolls  of  a  special  form  into  flat  bars  about  7,^" 
wide  which  are  cut,  piled,  and  reheated  in  a  bath  of  slag,  by 
which  means   their  percentage  of  carbon  can  be  reduced  as 
desired;  the  piles  are  then  rolled  into  the  desired  shape. 

The  Wenstrom  mill  is  a  modification  of  a  universal  plate 
mill,  designed  principally  for  rolling  flats.  Instead  of  acting 
upon  the  top  and  bottom  and  the  two  sides  at  different  times, 
it  does  this  simultaneously.  The  top  roll  can  be  adjusted 
vertically,  and  the  bottom  roll  transversely,  whereby  pieces 
of  different  thickness  and  width  can  be  produced  with  the 
same  set  of  rolls. 

Williams'  mill  consists  of  two  trains  of  different  size  rolls 
designed  for  producing  small  bars. 

Certain  modifications  in  details  of  wire  rod  mills  have  been 
introduced  by  Martin  and  Beavis,  and  F.  H.  Daniels. 

Rolling  Crack.— See  Crack. 

Rolling  Furnace. — See  page  312. 

Rolling  Hardness. — See  Hardness. 

Rolling  Mill. — See  page  403. 

Rolling  Mills,  Classification  of. — See  page  409. 


ROLLING  OFF— RUB  UP  421 

Rolling  Off. — (i)  In  rolling:  see  page  408;  (2)  of  tubes:  see  page 
490. 

Rolling  On. — Of  tubes:  see  page  490. 

Rolling  Open  Hearth  Furnace. — See  page  312. 

Ronay  Process. — See  page  44. 

Rontgen  Ray  Spectrometer. — In  the  study  of  crystals :  see  page  1 20. 

Roofing  Tin.— See  page  433. 

Roozeboom's  Equilibrium  Diagram. — See  page  272. 

Rope  Driven. — See  page  407. 

Ropiness  (Eng.)- — A  term  applied  to  steel  when  side  ruptures  occur 
in  ingots  which  are  being  rolled  down. 

Rose;  Rose  Steel. — See  page  135. 

Rosenhain's  Amorphous  Cement  Theory. — See  page  282. 

Rosenhain's  Equilibrium  Diagram. — See  page  272. 

Rosenhain  and  Haugh ton's  Reagent. — For  etching:  see  page  288. 

Rosetti  Radiation  Pyrometer. — See  page  207. 

Rossi's  Process. — This  is  somewhat  similar  to  Goldschmidt's, 
employing  aluminum  for  the  reduction  of  metals  from  their 
ores  or  oxides.  A  bath  of  molten  aluminum  is  used  and  on 
this  the  ore  is  thrown.  This  bath  is  usually  maintained  in  an 
electric  or  other  type  of  furnace  so  any  additional  heat  required 
may  easily  be  supplied. 

Rotary  Kiln  Process. — See  page  45. 

Rotary  Movement. — See  page  281. 

Rotary  (Rotating)  Puddling  Furnace;  Machine. — See  page  379. 

Rotary  Shears. — See  Shears. 

Rotary  Squeezer. — See  page  377. 

Rotation  Effect. — Of  oblique  light:  see  page  127. 

Rotator. — See  page  379. 

Rotten ;  Rottenness. — A  piece  of  metal  is  said  to  be  rotten  when,  on 
account  of  burning,  high  sulphur,  or  imperfect  deoxidation  in 
manufacture,  it  crumbles  or  falls  to  pieces,  or  cracks  when  rolled 
or  forged;  a  term  rarely  applied  to  brittleness. 

Rough  Fracture. — See  page  178. 

Rough  Roller. — See  page  414. 

Roughened  Tin  Plate.— See  page  433. 

Roughing. — (i)  In  general,  preliminary,  as  roughing  rolls,  roughing 
passes  (of  ingots,  etc.),  roughing  out  (machining),  etc.;  (2)  rag- 
ging (Eng.) :  see  page  407. 

Roughing  Block. — In  wire  drawing:  see  page  508. 

Roughing  Cinder. — See  Slag. 

Roughing  Hole  (South  Staffordshire). — In  old  blast  furnaces  pro- 
vided with  a  tymp,  etc.,  a  hole  in  the  runner  at  the  bottom  of  the 
cinder  fall,  where  the  cinder  was  collected  around  an  iron  rod  and 
so  removed. 

Roughing  Loam. — See  page  301. 

Roughing  Roll;  Roller;  Stand. — See  page  403. 

Roughing  Cinder;  Slag.— See  Slag. 

Round. — In  charging  a  blast  furnace:,  see  page  33. 

Round  Top  Furnace. — See  page  313. 

Rowling  (obs.). — Rolling. 

Rub  Up  (Eng.). — To  stir  up  or  rabble  a  metallic  bath. 


422  RUBBLE— RUTHENBURG  PROCESS 

Rubble. — (i)  Rabble;  (2)  a  mixture  of  gravel  and  cement. 

Rubble  Ironstone. — See  page  244. 

Rudolphs -Landin  Process. — See  page  145. 

Ruelle  Test.— See  page  482. 

Ruff's  Equilibrium  Diagram. — See  page  272. 

Rumble;  Rumbling  Mul. — See  page  58. 

Run  (verb). — (i)  Of  a  crucible:  see  page  113;  (2)  of  a  cupola:  see 

page  182. 

Run  Down;  Running  Down. — Of  a  cupola:  see  page  182. 
Run  a  Melt. — Melting  iron  in  a  cupola  for  foundry  work. 
Run-of-Mine  Coal. — See  Coal. 
Run-out  Fire. — See  page  383. 
Run  Steel. — See  page  257. 
Runner. — (i)  Of  a  blast  furnace:  see  page  36;  (2)  of  a  casting: 

see  pages  57  and  299. 
Runner  Head.— See  page  57. 
Running  Mold. — See  page  57. 
Running-out  Fire. — See  page  383. 
Running  Stopper. — See  Ladle. 

Runnings  (obs.). — Molten  metal  from  a  blast  furnace. 
Rupture. — See  pages  177  and  330. 
Rupture  by  Bursting. — See  page  179. 
Russell  Test. — See  page  482. 
Russia  Iron;  Russian  Sheet  Iron. — See  page  431. 
Rust. — See  pages  106  and  367. 
Rust  Coating. — For  wire:  see  page  507. 
Rust  Proof  Coating. — See  page  367. 
Rust  Proof  Processes. — See  page  367. 
Ruthenburg  Process.— See  page  163. 


S. — Chemical  symbol  for  sulphur,  q.v. 

Sa. — Chemical  symbol  for  samarium:  see  page  84. 

Sb. — Chemical  symbol  for  antimony  (Latin,  stibium},  q.v. 

Sc. — Chemical  symbol  for  scandium:  see  page  84. 

Se..— Chemical  symbol  for  selenium:  see  page  84. 

Si. — Chemical  symbol  for  silicon,  q.v. 

Sn. — Chemical  symbol  for  tin  (Latin,  stannum),  q.v. 

ST. — Chemical  symbol  for  strontium:  see  page  84. 

S.A.E. — Society  of  Automotive  (formerly  Automobile)  Engineers. 

S.C.I. — Swedish  charcoal  (wrought)  iron. 

S.W.G. — (i)  Steel  wire  gage;  (2)  British  standard  or  imperial 
wire  gage;  (3)  Stubs'  wire  gage. 

Sack  Mill. — See  page  420. 

Sackur's  Theory. — Of  passivity:  see  page  364. 

Sadden  or  Saddening  Heat. — See  page  116. 

Safe  Load ;  Range  of  Stress. — See  page  468. 

Safety,  Factor  of.— See  page  468. 

Sag;  Sagg. — To  (cause  to)  sink  down  or  become  compacted. 

Saggar;  Sagger. — (i)  In  -making  crucibles:  see  page  112;  (2)  for 
malleable  castings:  see  page  258;  (3)  in  molding:  see  page  300. 

St.  Chamond  Armor  Plate. — See  page  9. 

St.  Etienne  Process. — See  page  64. 

Sainte-Claire-Deville  Gas  Pyrometer. — See  page  207. 

Saklatwalla's  Iron -Phosphorus  Diagram. — See  page  272. 

Sal  ammoniac. — Commercial  ammonium  chloride. 

Salamander. — (i)  The  old  name  for  the  bloom  from  a  direct 
furnace  (see  page  135);  (2)  the  iron  forming  the  scaffold  in  a 
cupola  (rare);  (3)  a  stove,  usually  cylindrical  in  shape,  made  of 
plates  and  filled  with  coke  or  coal,  for  warming  portions  of  a  mill 
building,  particularly  to  prevent  the  freezing  up  of  valves  and 
pipes;  (4)  the  infusible  mass  found  in  the  hearth  of  a  blast 
furnace  when  it  is  torn  out  for  relining;  also  called  bear,  sow,  or 
horse.  This  may  consist  of  (a)'  iron  containing,  considerably 
lower  carbon  than  the  regular  pig  iron,  and  (b)  a  copper-colored 
substance  composed  principally  of  cyano-nitride  (nitro-cyanide) 
of  titanium,  to  which  the  formula  (Ti6CN)4  has  been  given. 
Contained  in,  or  associated  with,  this  bear  or  salamander  is  what 
has  been  erroneously  termed  amianthus  (the  name  of  a  variety 
of  asbestos),  or  furnace  amianthus:  "It  is  white,  and  of  a  finely 
fibrous  structure  (fibrous  silica),  and  here  and  there  it  is  distinct- 
ly seen  to  consist  of  more  or  less  globular  aggregations  of  radiating 
fibers.  It  is  associated  with  minute  brilliant  crystals  of  cyano- 
nitride  of  titanium,  and,  freed  from  these  it  was  found  by  analysis 
to  contain  97.5%  SiOa  with  traces  of  lime  and  manganese" 
(Percy) 

423 


424         SALAMANDER  FURNACE— SAW  FILE  TEMPER 

Salamander  Furnace. — See  page  147. 

Salom's  Formula. — For  tensile  strength:  see  page  339. 

Salt. — (i)  Ordinary  salt,  sodium  chloride,  NaCl;  (2)  the  combina- 
tion of  an  acid  with  a  base:  see  page  88. 

Salzburg  Process. — See  page  78. 

Sample  Spoon. — See  Spoon. 

Sampling  Pig  Iron. — See  page  349. 

Sand. — (i)  Of  ingots:  see  page  56;  (2)  as  a  flux:  see  page  176; 
(3)  as  a  refractory:  see  page  395. 

Sand  Blower. — See  page  492. 

Sand  Boil. — See  page  314. 

Sand  Bottom. — See  Lining. 

Sand  Cast  Pig. — See  page  342. 

Sand  Core  Process. — See  page  65. 

Sand  Mold.— See  page  296. 

Sandberg  Process.— See  page  233. 

Sandstone.— See  page  395. 

Saniter  Desulphurizing  Process. — See  page  387. 

Saniter's  Reagent. — For  hot  etching:  see  page  287. 

Saniter  Steel. — Steel  made  by  the  Saniter  desulphurizing  process: 
see  page  387. 

Saniter  Wear  Test.— See  page  480. 

Sankey  Test— See  page  482. 

Sap. — In  cementation:  see  page  71. 

Sappy  Fracture.— See  page  178. 

Sarnstrom  Process. — See  page  145. 

Satisfied. — Combined,  so  that  the  substance  has  no  further  chemical 
affinity  under  the  existing  conditions,  as  lime  combined  with  the 
requisite  amount  of  silica;  this  term  must  be  distinguished  from 
saturated. 

Sattman  and  Hornatsch  Process. — See  page  145. 

Saturated  Austenoid. — See  page  275. 

Saturated  Compound. — See  page  85. 

Saturated  Martensite. — See  page  276. 

Saturated  Solution.— See  Solution. 

Saturated  Steel. — See  page  273. 

Saturated  Vapor. — See  page  202. 

Saturator. — Of  by-product  gas:  see  page  96. 

Saucer  Bosh. — See  page  27. 

Saunderson  Process. — See  page  64. 

Sauveur's  Critical  Strain. — See  page  216. 

Sauveur's  Equilibrium  Diagram. — See  page  272. 

Sauveur's  Formulae. — For  tensile  strength  and  elongation:  see 
page  339. 

Sauveur's  Hypothesis. — On  the  allotropic  transformation  of  iron: 
see  page  278. 

Sauveur  Process. — (i)  For  sound  ingots:  see  page  60;  (2)  of 
coarsening  ferrite:  see  page  216. 

Sauveur's  Reagent. — For  etching:  see  page  287. 

Sauveur  and  Whiting's  Thermomagnetic  Selector.— See  page  210. 

Saw  File  Temper.— See  Temper. 


SCAB— SCORIA  PROCESS  425 

Scab,  Scabby. — (i)    On  castings:   see  page   58;    (2)  a  defect  in 

plates,  etc.:  see  page  357. 
Scaffold. — See  page  35. 

Scaffolding  Down. — Of  a  blast  furnace:  see  page  37. 
Scale. — (i)  The  coating  of  oxide  which  forms  on  the  surface  of 

metal  which  is  heated.     This  scale  is  cracked  and  broken  off 

during  working,  and  according  to  the  method  is  termed  roll  scale 

(mill  scale)  or  hammer  scale;  (2)  usually  scales:  an  instrument 

for  weighing,  usually  heavy  bodies. 
Scale  Pit. — See  page  407. 
Scaled  Casting. — See  page  258. 
Scaling. — (i)  Of  drawings  or  blue  prints,  measuring  dimensions 

with  a  scale  instead  of  depending  on  dimensions  as  marked:  an 

inaccurate  method;  (2)  a  defect:  see  Pit. 
Scalping. — Of  crucibles:  see  page  112. 
Scar. — In  a  blast  furnace:  see  page  38. 
Scarf. — (i)  To  bevel  (also  the  bevel)  the  edges  of  skelp  in  the  process 

of  making  lap- welded  pipe:  see  page  489;  (2)  to  hollow  the  side 

of  a  shaft,  etc.,  in  forging. 
Scarf  Weld;  Joint. — See  page  502. 
Scarfing  Test. — See  page  476. 

Scattering. — Of  liquid  steel  in  a  mold,  etc.,  spitting. 
Scelp  (Eng.).— Skelp. 

Schaffer  and  Budenberg's  Thalpotassimeter. — See  page  210. 
Schamotte. — See  page  396. 
Schiebler  Process. — See  page  22. 
Schillerization.— See  page  127. 
Schiseophone. — See  page  483. 
Schmidhammer  Process. — See  page  145. 
Schneider  et  Compagnie  Process.— See  page  230. 
Schneider-Creusot  Furnace. — See  page  163. 
Schneider  Furnace.— See  page  163. 
Schb'nawa-Rodenhauser  Furnace. — See  page  162. 
Schoop  Process. — See  page  373. 
Schreibersite. — See  page  292. 
Schulte-Hemmis  Process. — For  producing  hollow  bodies  or  shells 

from  malleable  metals,  chiefly  by  pressure. 
Schumacher  Process. — See  page  44. 
Schungite. — See  Carbon. 
Schwartz  Process. — See  page  319. 
Sclerometer. — See  page  480. 
Scleroscope. — See  page  478. 

Scobel- Johnson  Apparent  Elastic  Limit. — See  page  470. 
Scobel's  Yield  Point.— See  page  470. 
Scone  (Scotch). — A  fireclay  disk  or  biscuit  used  in  patching  the 

lining  of  furnaces,  etc. 
Scorched  Fracture. — See  page  178. 
Scorched  Ingot  (Eng.). — See  page  57. 
Scoria;  Scoriae  (plur.). — See  Slag. 
Scoria  Block;  Plate. — See  page  32. 
Scoria  Process. — See  page  44. 


426  SCORIACEOUS— SEAM 

Scoriaceous. — Like  or  resembling  cinder.  A  term  applied  to  a 
structure  presenting  the  appearance  of  slag.  A  term  which  has 
been  used  when  the  exact  nature  of  .the  substance  is  not  known 
when  detected  as  inclusions  in  metals  and  alloys  (I.A.T.M.). 

Scoride  (rare). — Cinder. 

Scorodite. — See  page  244. 

Scotch  Iron. — See  page  350. 

Scotch  Tuyere. — See  page  31. 

Scott  process. — See  page  61. 

Scouring;  Scouring  Barrel.— See  page  507. 

Scouring  Cinder. — See  Slag. 

Scrag  (Eng.). — To  straighten  a  spring,  etc.,  which  has  been  cam- 
bered (bent),  by  pushing  in  the  bulge  and  releasing. 

Scrap;  Scrapping. — (i)  In  the  Bessemer  process,  throwing  steel 
scrap  into  the  vessel  when  the  metal  is  blowing  too  hot;  (2)  of 
molds,  removing  the  steel  which  has  run  over  the  top  and  down 
the  sides  during  pouring;  (3)  in  general  parlance,  discarding 
anything,  such  as  machinery,  which  is.  out  of  date  or  wornout; 
also  the  material  which  is  discarded.  See  Discard. 

Scrap  Ball;  Bar;  Furnace;  Iron.— See  page  379. 

Scrap  and  Pig  Process ;  Scrap*  Process. — Usually  called  pig  and 
scrap  process:  see  page  310. 

Scraper. — See  page  415. 

Scratch  Hardness. — See  page  331. 

Screen. — A  large  sieve  used  for  separating  fine  from  coarse  material. 
It  consists  of  woven  wire,  or  of  a  steel  plate,  having  holes  whose 
size  depends  upon  the  fineness  of  the  product  required.  A 
revolving  screen  is  a  revolving  cylinder  made  of  steel  plates, 
generally  inclined  slightly  downward  so  that  material  will  move 
forward  by  gravity,  and  usually  having  holes  of  a  different  size 
in  different  parts,  the  smaller  being  at  the  upper  end. 

Screw  Down. — See  page  414. 

Scribe  Method;  Scriber  Method  (Eng.).— For  yield  point:  see 
page  470. 

Scroll  Bundle.— See  Coil. 

Scrubber. — For  gas:  see  page  33. 

Scruff;  Scruffy. — The  dirt  or  impurities  on  the  surface  of  an  object 
causing  roughness;  also  the  condition. 

Scull.— See  Skull. 

Scum. — See  page  115. 

Scurf.— To  flake  off,  or  the  material  which  flakes  off;  dross. 

Sea  Coal.— See  Coal. 

Seam. — (i)  In  tubes:  see  page  489;  (2)  in  welding:  see  page  502. 

Seam. — Also  called  roak  or  roke  (Eng.);  a  crack  on  the  surface  of 


very  tme  it  may 
hair  crack  or  hair  seam.  A  lap  seam,  lap,  cold  lap,  or  cold  shut 
is  produced  when  a  fin  or  ridge  is  formed  and  doubled  over  in 
forging  or  rolling.  A  snake  or  streak  is  a  long  wavy  seam. 
Longitudinal  and  transverse  seams  are  those  extending  length- 
wise or  crosswise  respectively  of  the  piece  as  produced.  A 


SEAMLESS  TUBE— SEMI-CONTINUOUS  MILL      427 

spiral  seam  occurs  in  the  manufacture  of  seamless  tubing  when  a 
surface  defect  is  extended  spirally  in  the  process  of  piercing. 

Seamless  Tube.— See  page  490. 

Season. — Of  crucibles:  see  page  112. 

Season  Crack. — See  Cold  Working. 

Seaton  and  Jude  Test. — See  page  482. 

Seaton  Test.— See  page  482. 

Sebenius  Process. — See  page  62. 

Seconds. — Of  sheets:  see  page  433. 

Second  Annealing. — Of  sheets:  see  page  431. 

Second  Class  Foam  Cells. — See  page  121. 

Second  Order  Cells. — See  page  121. 

Second  Pickling. — Of  sheets:  see  page  431. 

Second  Strand. — See  page  415. 

Secondary  Crystals. — See  page  121. 

Secondary  Crystallization. — See  page  121. 

Secondary  Furnace. — See  page  316. 

Secondary  Gas. — See  page  33. 

Secondary  Hardening. — See  page  447. 

Secondary  Metals. — The  term  secondary  is  applied  to  metals 
recovered  from  scrap  metal,  sweepings,  skimmings,  drosses,  etc., 
as  distinguished  from  primary  metals  which  are  obtained  direct 
from  ore.  The  term  "secondary"  carries  no  implication  of 
inferiority  in  quality  (terms  as  used  by  the  U.  S.  Geol.  Survey). 

Secondary  Slip. — See  page  283. 

Secondary  Stress. — See  page  332. 

Secondary  Twinning. — See  page  123. 

Sectile. — See  page  124. 

Section;  Section  Area. — See  page  468. 

Section  of  Failure. — See  page  337. 

Section  Mill. — See  page  409. 

Seger  Cones. — See  page  209. 

Seggar. — See  pages  112  and  300. 

Segregans. — Mother  metal:  see  page  56. 

Segregate. — See  page  56. 

Segregated  Cementite. — See  page  273. 

Segregated  Spot.— See  Hard  Spot. 

Segregation.— See  pages  55  and  442. 

Segregation  Deficit;  Excess.— See  page  56. 

Seguin  Process. — See  page  229. 

Selective  Corrosion. — See  page  106. 

Selective  Effect. — Of  oblique  light:  see  page  127. 

Selective  Freezing. — See  page  266. 

Selective  Transformation. — See  pages  271  and  275. 

Selenium,  Action  of  Light  on. — See  page  208. 

Self -corrosion. — See  page  108. 

Self -fluxing  Ore. — See  page  243. 

Self -hardening  Steels.— See  pages  446  and  451. 

Self -roasting  Ore.— See  page  243. 

Self -strained;  Self -stressed.— See  page  332. 

Semicombined. — See  page  83. 

Semi-continuous  Mill. — See  page  416. 


428  SEMI-CRYSTALLINE  STRUCTURE— SHEARS 

Semi-crystalline  Structure.— See  page  125. 

Semi-direct  Process;  Recovery  Process.— In  by-product  coke 
ovens:  see  page  96. 

Semi-finished.— See  Finished. 

Semi-finished  Products;  Mills  for. — See  page  411. 

Semimetal  (obs.). — Metalloid;  possessed  of  some  but  not  all  the 
(physical)  properties  of  a  metal. 

Semi-products. — See  page  411. 

Semi-steel. — Also  called  toughened  cast  iron  or  Sterling's  tough- 
ened cast  iron;  it  is  produced  by  melting  about  one-third  to 
one-fifth  by  weight  of  wrought  iron  or  soft  steel  scrap  with 
cast  iron,  usually  in  a  cupola,  and  is  employed  in  the  manufacture 
of  castings,  known  as  semi-steel  castings. 

Semi-steel  Casting.— See  Semi-steel. 

Semi-water  Gas. — See  Producer. 

Semi-wild. — Same  as  lively,  q.v. 

Sensible  Heat.— See  page  199. 

Sentinel;  Sentinel  Pyrometer. — See  page  209. 

Set.— (i)  Of  steel  ingots,  etc.,  after  pouring,  when  a  skin  or  crust  of 
sufficient  thickness  has  formed,  so  that  when  the  molds  are 
removed  the  metal  will  not  run  out;  (2)  distortion:  see  page  334. 
(3)  in  coating  sheets:  see  page  432. 

Set  Temper.— See  Temper. 

Setter  In. — In  the  crucible  process:  see  page  114. 

Setting  Down. — In  forging:  see  page  177. 

Settling  Head. — See  page  56. 

Settling  Tank. — In  the  purification  of  water,  a  tank  in  which  muddy 
water  or  water  which  has  been  chemically  treated,  is  allowed  to 
stand  until  the  impurities  have  collected  on  the  bottom. 

Seventy-two  Hour  Coke.— See  page  95. 

Shackles. — Of  a  testing  machine:  see  page  469. 

Shadow  Line.— See  page  289. 

Shaft. — (i)  The  interior  of  a  shaft  furnace  above  the  boshes;  (2)  a 
circular  bar  or  rod  of  steel  used  for  conveying  power  by  rotation. 

Shaft  Furnace. — Seepages  114  and  181. 

Shaft  Washer.— See  Ore. 

Shake  Down. — See  page  314. 

Shaking  Barrel. — See  page  58. 

Shank;  Shank  Ladle.— See  Ladle. 

Shape  Mill. — See  page  409. 

Shape  Work. — See  Hammer. 

Shaped  Bloom.— See  page  417. 

Shaping  Process  (Howe). — For  giving  to  material  a  desired  form  or 
shape  as  by  rolling  or  forging  (working)  or  by  melting  and 
casting  in  molds. 

Sharp. — (i)  Of  a  casting:  see  page  58;   (2)  of  a  flame;  oxidizing. 

Sharps. — See  page  432. 

Shaw  Process. — (i)  For  casting:  see  page  65;  (2)  for  purifying: 
see  page  387. 

Shears. — A  machine  for  cutting  up  or  dividing  pieces  of  metal 
consisting  of  two  knife  blades,  one  of  which  is  fixed  and  the  other 
movable  and  operated  up  and  down  (rarely  sideways)  by  steam 


SHEAR  BLADE  TEMPER— SHEETS  429 

or  electrically  driven  gears  or  by  hydraulic  power.  The  usual 
gear-driven  shears  has  the  upper  movable  knife  set  at  a  slight 
angle  (rake)  to  the  lower  and  is  termed  a  guillotine  shears; 
its  advantage  is  that  only  a  small  part  of  the  edge  is  cutting  at  one 
time  and  hence  less  power  is  required  than  if  the  edges  are 
parallel.  A  rotary  shears,  for  producing  round  plates,  has  a 
horizontal  revolving  table  to  which  the  plate  is  fastened,  and  set 
at  the  proper  distance  are  two  vertical  disks,  one  above  the  other 
and  arranged  so  their  edges  slightly  overlap;  they  revolve  in 
opposite  directions  and  cut  off  the  edge  of  the  plate  between 
them.  A  type  frequently  used  for  cutting  up  scrap,  muck  bar, 
etc.,  called  alligator  shears,  crocodile  shears,  lever  shears,  or 
cropping  shears,  has  two  jaws,  one  of  which  is  fixed  while  the 
other  is  pivoted  and  actuated  by  a  cam  arrangement. 

Shear  Blade  Temper. — See  Temper. 

Shear  Steel. — Also  called  sheared  steel  or  German  steel  (obs.). 
It  is  the  product  obtained  by  welding  and  forging  plated  bars 
(see  page  71),  and  is  made  principally  in  England.  These 
bars  are  broken  into  suitable  lengths,  six  piled  together,  con-, 
stituting  a  fagot,  covered  with  fireclay  and  borax  to  prevent 
excessive  oxidation,  and  drawn  out  under  a  hammer  into  a 
bar  (single  shear  steel).  If  this  bar  is  doubled  and  rehammered 
it  is  known  as  double  shear  steel.  The  product  is  used  for 
articles  of  cutlery,  etc. 

Sheared  Plate  Mill. — See  page  413. 

Shearing. — In  general,  cutting:  see  also  page  101. 

Sheared  Steel.— See  Shear  Steel. 

Shearing  Modulus  of  Elasticity. — See  page  335. 

Shearing  Resilience. — See  page  33.1. 

Shearing  Strength. — See  page  330. 

Shearing  Stress. — See  page  332. 

Shearing  Test. — See  page  477. 

Sheathing. — A  protective  outside  coating  or  jacket  of  metal  or 
wood. 

Sheet.— See  below. 

Sheet  Bar. — See  page  411. 

Sheet  Furnace.— See  page  430. 

Sheet  Gage. — See  page  188. 

Sheets,  Manufacture  of. — See  page  430. 

Sheet  Metal  Gage.— See  page  188. 

Sheet  Mill. — See  page  430. 

Sheets  and  Tin  Plate. — The  dividing  line  between  sheets  and 
plates  is  not  sharply  drawn,  but  depends  principally  upon  the 
type  of  mill  on  which  they  are  rolled;  it  may  roughly  be  taken 
that  plates  are  %"  thick  and  over,  and  sheets  thinner  than  this. 
U.  S.  Government  has  set  the  limit  for  sheets  at  No.  10  U.  S. 
Standard  Gage.  Tin  plates  (tinned  plates). are  sheets  (usually 
of  light  gage)  coated  with  tin  to  protect  them  from  corrosion;  if  of 
heavy  gage,  they  are  sometimes  called  tinned  sheets.  The 
material  used  in  the  manufacture  comes  in  the  form  called  generi- 
cally  sheet  bars;  those  for  tin  plates  are  also  called  specifically 
tin  bars  or  tin  plate  bars.  The  mills  on  which  these  bars  are 


430  SHEETS  AND  TIN  PLATE 

rolled  into  sheets  are  of  the  two-high,  non-reversing  type  known 
as  pull  over  (see  page  408),  and  are  classed  as  sheet  mills  and  tin 
mills.  As  a  rule  sheet  mills  do  not  roll  much  below  No.  28  gage, 
although  they  can  go  down  to  about  No.  30;  tin  mills  commonly 
do  not  go  above  No.  20  although  they  can  go  up  to  No.  16.  In 
this  country  sheets  are  started  in  one  stand  of  rolls  and  finished 
in  another  (double  mill) ;  tin  plates  are  rolled  in  one  stand 
(single  mill). 

Manufacture  of  Sheets. — With  extra  heavy  sheets  only 
one  is  rolled  at  a  time,  and  is  called  a  single  (single  steel). 
Ordinarily  two  bars  are  rolled  simultaneously  and  are  called  a 
pair  (the  sheets  are  then  doubles  or  double  steel),  and  the  small 
reverberatory  furnace  in  which  they  are  heated,  a  pair  furnace. 
In  rolling  pairs  the  bars  are  put  successively  through  the  rolls 
by  the  roller  and  are  seized  on  the  other  side  by  another  man 
(the  catcher)  who  places  each  on  top  of  the  top  roll,  to  be  taken 
off  by  the  roller  as  the  other  is  going  between  the  rolls.  After 
receiving  a  certain  amount  of  reduction  they  are  taken  to  the 
finishing  stand  where  they  are  rolled  separately  still  further, 
and  then  one  is  laid  on  top  of  the  other  and  rolling  is  continued 
until  they  are  too  cold.  The  rolls  become  heated,  particularly 
in  the  middle,  which  causes  a  certain  amount  of  expansion; 
this  is  partially  offset  by  turning  them  slightly  concave  in  a 
lathe;  if  the  expansion  is  extreme,  the  rolls  are  said  to  be  puffed. 
After  the  last  rolling  the  two  sheets  are  separated  and  a  number, 
depending  upon  the  desired  gage,  piled  together  in  a  pack,  the 
longer  ones  on  the  bottom,  this  operation  being  known  as  match- 
ing, and  the  man  who  attends  to  it  the  matcher.  They  are  now 
bent  double  transversely  and  the  bend  stamped  flat  by  a  machine 
called  a  doubler,  a  form  of  hammer  having  a  long  flat  face.  If 
the  doubler  forms  part  of  a  shear  (in  the  case  of  light  sheets) 
of  the  crocodile  type,  it  is  termed  a  doubling  shear.  The  packs 
are  reheated  in  the  sheet  furnace  (a  rash  is  occasioned  when  the 
outside  is  heated  much  hotter  than  the  interior)  and  rolled  down 
to  the  desired  gage,  after  which  the  packs  are  sheared  and  opened, 
i.e.,  the  sheets  are  pulled  apart.  Sheets  difficult  to  separate  are 
called  stickers.  The  operation  is  usually  performed  by  pulling 
the  sheets  off  by  hand,  or,  in  the  case  of  stickers,  with  a  pair  of 
tongs,  the  rest  of  the  pack  being  held  down  with  the  foot.  In 
some  cases  the  strip  sheared  from  the  edge  of  a  pack,  held  in  one 
hand  like  a  sword,  is  brought  down  between  two  stickers,  which 
is  called  swording  stickers.  To  prevent  sheets  from  sticking 
during  hot  rolling,  it  was  at  one  time  the  practice,  in  certain 
localities,  to  sift  coal  slack,  sawdust,  etc.,  between  them,  called 
dusting;  this  practice  has  been  almost  entirely  abandoned. 
Horns  are  projections  at  the  end  of  a  sheet  caused  by  the  sides 
rolling  out  longer  than  the  middle.  Jumping  is  where  a  sheet 
slips  when  the  pack  is  rolled,  causing  buckling  or  lapping  by  the 
rolls.  Such  a  sheet  bent  or  doubled  over  is  called  a  lapper, 
pinched  sheet,  or  simply  a  pincher.  Almost  no  sheets  are  sold  as 
they  come  from  from  the  hot  rolls;  in  this  condition  they  are 
known  as  red  hard  sheets.  Practically  all  the  product  is  an- 


-  SHEETS  AND  TIN  PLATE  431 

nealed  to  be  sold  as  black  plate  (finished  black  plate)  or  is  coated 
with  zinc  for  galvanized  sheets.  For  annealing  they  are  piled  on 
a  bottom,  and  covered  with  a  steel  or  iron  box  (annealing  box, 
annealing  pot)  to  exclude  the  air,  the  operation  being  known  as 
close  annealing  or  box  annealing.  They  are  then  heated  in  a 
furnace  to  about  760°  to  870°  C.  (1400°  to  1600°  F.),  which  re- 
quires, altogether,  about  1 6  to  20  hours.  The  top  sheets  from  var- 
ious piles  are  known  as  outsides,  and  are  oxidized  more  than  the 
others.  By  another  method,  known  as  blue  annealing,  the 
sheets,  if  fairly  heavy,  are  allowed  to  cool  slowly  after  the  hot 
rolling,  or  if  of  lighter  gage,  as  is  usually  the  case,  they  are  passed 
singly  through  an  open  furnace  where  they  are  reheated  to  the 
proper  temperature  for  the  annealing  or  softening  operation.  As 
the  name  indicates,  they  have  a  bluish-black  appearance.  Aside 
from  the  color  of  the  sheets,  the  properties  resulting  from  the  two 
methods  are  practically  the  same.  This  method  is  also  known  as 
open  annealing,  the  sheets  being  exposed  directly  to  the  air.  For 
galvanizing  they  are  now  pickled  for  5  to  10  minutes  in  dilute  sul- 
phuric acid  to  remove  the  scale,  being  held  loosely  in  racks  or 
cradles  so  the  acid  may  penetrate  between.  They  are  next  washed 
with  water  (swilled)  in  tanks  to  remove  the  acid,  and  are  kept  sub- 
merged in  water  until  just  before  they  are  galvanized,  when  they 
are  put  for  a  few  minutes  in  a  very  weak  solution  of  acid.  Galvan- 
izing is  effected  by  passing  the  sheets  through  the  galvanizing  pot 
or  kettle,  a  deep  iron  vessel  filled  with  molten  spelter  (commercial 
zinc),  this  method,  which  is  always  used  for  sheets,  being  termed 
pot  galvanizing.  The  markings  or  spangles  on  the  surface  of 
galvanized  sheets  is  due  to  the  crystallization  of  the  zinc,  the  size 
depending  upon  the  rate  of  cooling.  Russian  sheet  iron  or 
Russia  iron  is  a  special  grade  of  sheet  with  a  glossy  black,  slightly 
mottled  appearance  due  to  oxide  adhering  to  the  surface  so 
tenaciously  that  it  cannot  be  cracked  off  by  repeated  bendings. 
It  is  produced  by  hammering  a  pile  of  heated  sheets  having  very 
slight  projections  or  indentations  on  the  surface,  with  or  without 
charcoal  powder  sifted  between  before  heating.  Sheets  ham- 
mered in  this  way  to  get  a  polished  surface  are  said  to  be  planished 
(rarely  called  glanced  sheets). 

Manufacture  of  Tin  Plates. — The  process  up  to  the  anneal- 
ing operation  is  practically  the  same  as  that  for  the  manufacture 
of  sheets.  Here,  however,  there  is  a  slight  change.  The  plates 
are  first  pickled  (black  pickling  or  first  pickling)  as  already 
described.  After  swilling  they  are  annealed  in  boxes  (black 
annealing  or  first  annealing),  and  are  then  cold  rolled,  i.e.,  given 
a  number  of  passes  (usually  three)  cold  through  rolls  (cold  rolls) 
to  make  the  surface  perfectly  smooth  so  the  finished  tin  plate 
will  have  a  high  polish.  As  this  renders  them  somewhat  stiff 
they  are  reannealed  (white  annealing  or  second  annealing) 
at  a  slightly  lower  temperature  than  before.  Plates  may  be 
sold  simply  cold  rolled  or  cold  rolled  and  annealed.  If  to  be 
tinned  they  are  again  pickled  (white  pickling  or  second  pickling) 
and  swilled.  They  are  then  passed  through  a  pot  filled  with 
molten  tin  (white  pot,  tin  pot,  tinning  pot) .  According  to  modern 


43 2  SHEETS  AND  TIN  PLATE  - 

methods  the  coating  of  sheets  is  performed  in  one  operation  by 
passing  them  through  the  pot  of  molten  metal  between  driven 
rollers  arranged  in  pairs,  the  last  pair  squeezing  off  the  surplus 
metal.  In  England  these  mechanical  tinning  pots  are  sometimes 
called  patents.  The  necessary  equipment  for  coating  tin  or 
terne  plates  is  called  a  set :  For  terne  and  coke  plates  it  consists 
of  a  pot  containing  tin  or  the  terne  mixture  covered  with  palm 
oil,  and  rolls;  for  charcoal  plates  there  are  a  palm  oil  tin  pot,  a 
wash  pot,  and  a  roll  pot  (each  separate).  A  combination  pot 
means  a  white  pot  with  rolls  and  then  a  tin  pot  with  rolls.  The 
early  method  of  tinning,  called  dipping,  was  done  by  hand  and 
was  more  complicated.  The  cleaned  sheets  were  first  put  in  a 
pot  of  grease  (tinman's  pot)  the  temperature  of  which  was  very 
low.  A  number  of  plates  were  next  plunged  into  the  tin  pot 
containing  molten  tin  covered  with  grease.  From  this  they  were 
passed  to  the  larger  of  two  compartments  in  the  wash  pot  filled 
with  molten  tin  of  better  quality  than  in  the  tin  pot,  in  which 
they  could  remain  some  time  without  becoming  dry  (i.e.,  becom- 
ing so  hot  very  little  tin  would  adhere);  they  were  then  taken  out 
singly  and  rubbed  on  each  side  with  a  hemp  brush,  after  which 
they  were  redipped  in  the  smaller  compartment  of  the  wash 
pot,  containing  the  best  quality  of  tin,  to  obliterate  marks 
made  by  the  brush.  They  were  next  transferred  to  the  grease 
pot  (grease  pan)  filled  with  palm  oil,  or  palm  oil  and  tallow, 
at  a  fairly  high  temperature,  where  the  surplus  tin  drained  off, 
amounting  sometimes  to  two  or  three  times  what  remained 
on  the  plate.  They  next  went  to  the  cold  pot,  where  they  were 
allowed  to  cool  exposed  to  the  air.  The  excess  of  tin  draining 
off  the  plate  left  an  accumulation  (wire  or  list)  at  the  bottom 
edge  which  was  removed  by  dipping  in  the  list  pot,  a  pot  con- 
taining a  layer  of  molten  tin  about  %"  deep,  and  considerably 
above  its  melting-point.  When  the  wire  was  perfectly  fused 
it  was  removed  by  lifting  the  plate  and  giving  it  a  quick  blow 
with  a  stick.  The  plates  were  then  worked  in  troughs  with 
bran,  and  polished. 

The  surface  of  the  molten  tin  in  the  tin  pot  is  covered  with  a 
layer  of  palm  oil  to  prevent  oxidation  and,  as  some  of  this  adheres 
to  the  plates,  it  is  necessary  to  clean  them.  This  was  formerly 
done  by  hand  but  now  usually  by  a  machine  (branning  machine) 
through  which  the  plates  are  passed,  a  series  of  revolving  brushes 
applying  bran  or  a  mixture  of  sawdust  and  lime  to  the  surface. 
Sharps  (the  hard  part  of  wheat)  or  middlings  and  shudes  (the 
hulls  of  grain)  are  sometimes  used  for  this  purpose. 

A  patch,  or  black  patch,  on  tin  plates  is  a  stain  caused  by 
scale  which  has  not  been  properly  cleaned  off.  Black  edged 
or  smoky  edged  plates  are  of  infrequent  occurrence  and  are 
due  to  too  low  a  temperature  in  annealing;  they  coat  with  tin 
but  show  a  dark  stain  along  the  edge.  White  edged  plates, 
which  also  are  of  infrequent  occurrence,  are  those  which  have 
been  overheated  in  the  white  annealing;  they  do  not  coat  well 
either  with  tin  or  lead. 

Terne  plates  are  made  in  the  same  way  as  tin  plates,  except 


SHEETS   'AND  TIN  PLATE  433 

that  the  coating  consists  of  a  mixture  of  tin  and  lead,  running 
from  about  50  to  75%  tin,  ordinarily  about  70%.  The  surface 
has  a  dull  appearance  and  is  covered  with  markings  (mottles) 
caused  by  crystallization  of  the  mixture,  the  size  depending 
principally  on  the  rate  of  cooling.  According  to  whether  the 
plates  are  passed  through  dry  bran  or  bran  moistened  with 
oil,  they  have  a  dry  finish  or  an  oil  finish  respectively. 

Tin  and  terne  plates,  after  being  finished,  receive  a  final 
inspection  in  the  assorting  room,  all  first  quality  sheets  being 
known  as  primes,  if  of  inferior  quality  as  seconds,  while  all  badly 
defective  material  (wasters)  is  thrown  out.  They  are  then 
packed  in  boxes.  The  unit  of  measure,  irrespective  of  the  gage 
(which  is  always  shown),  is  known  as  the  base  box.  This  is 
figured  as  the  number  of  square  inches  on  one  side  of  each  plate, 
and  amounts  to  31,360  square  inches;  in  England  it  corresponds 
to  1 1 2  plates,  14"  X  20",  No.  30  gage,  weighing  112  pounds.  Ordi- 
nary plates  are  sheared  to  size  immediately  after  the  hot  rolling, 
but  those  of  small  size  may  be  cut  up  from  a  large  plate  after 
finishing.  When  required  to  be  very  accurate  as  to  size,  they 
may  be  trimmed  after  finishing,  when  they  are  known  as  re- 
squared  plates. 

Sheets  (usually  galvanized  for  roofing)  are  corrugated  by 
passing  between  a  pair  of  rolls  in  the  surface  of  which  corruga- 
tions (grooves)  have  been  cut  longitudinally.  In  England 
sheets  or  plates  of  20  gage  or  thicker  are  called  singles;  21  to  24 
gage,  doubles;  25  to  27  gage,  trebles  or  lattens;  and  those  down 
to  29  gage,  extra  lattens;  taggers  are  very  thin  plates  largely 
used  for  metal  tags.  Coke  plates  or  sheets  (coke  tins  or  cokes) 
were  formerly  those  made  from  iron  puddled  from  coke  pig,  and 
charcoal  plates  or  sheets  were  those  made  from  charcoal  hearth 
wrought  iron  or  from  iron  puddled  from  charcoal  pig;  at  present 
this  significance  has  been  lost  as  both  are  practically  always  made 
from  soft  steel  (either  Bessemer  or  open  hearth),  the  charcoal 
plates  carrying  a  heavier  coating  of  tin,  and  therefore  of  higher 
quality  (  and  price).  The  amount  of  coating  is  usually  shown  by 
letters,  the  numbers  increasing  with  the  thickness  of  coating,  as 
A,  and  AAAAA.  For  tobacco  cans  and  similar  purposes  the 
sheets  are  sometimes  not  cold  rolled  as  the  rougher  surface  takes 
more  tin  for  coating  and  has  a  dull  silvery  finish;  these  are  called 
roughened  tin  plates.  All  terne  plates  are  commonly  called 
roofing  tin.  Tinned  or  galvanized  sheets  were  at  one  time  called 
white  iron  and  an  artificer  in  them  a  whitesmith. 

The  Bray  continuous  sheet  mill  consists  of  six  sets  of  two- 
high  rolls  tandem,  the  bars  being  fed  separately,  and  two  arms 
engaging  the  rear  of  each  bar  and  moving  it  forward  squarely 
into  each  set  of  rolls.  After  passing  through  these  rolls  a  suffi- 
cient number  of  sheets  are  collected  in  a  matcher,  and  the 
resultant  pack  is  passed  by  feed  rollers  into  the  first  of  three 
sets  of  two-high  rolls,  also  set  tandem,  between  which  it  is 
carried  forward  by  chain  tables.  After  leaving  the  last  set 
the  pack  is  passed  through  a  vv^ter  bosh  and  thence  through 
an  opening  machine  in  which  the  plates  are  loosened.  The 
28 


434  SHELDON  PROCESS— SIBUT  PROCESS 

pack  is  then  doubled  in  a  roller  doubler,  reheated,  and  finished 
as  usual. 

The  Donner  continuous  sheet  mill  consists  of  four  sets  of 
two-high  rolls  set  tandem,  with  feed  tables  or  conveyors  between 
each  set.  At  a  sufficient  distance  from  the  last  of  these  to  allow 
matching  of  the  sheets  which  individually  had  received  the  four 
customary  passes,  two  additional  sets  of  two-high  rolls  are  placed 
tandem,  and  after  passing  through  these  the  pack  is  doubled, 
reheated,  and  finished  much  as  usual. 

Howell's  mill,  designed  for  rolling  sheets,  consists  of  a  bloom- 
ing train  followed  by  a  number  (usually  four)  of  stands  of  rolls 
on  the  continuous  principle. 

The  Wittgenstein  mill,  for  thin  plates  or  sheets,  consists 
of  a  Lauth  three-high  mill  for  roughing,  followed  by  five  stands 
of  two-high  rolls,  one  behind  the  other,  and  so  close  together 
that  the  plate  may  be  in  all  five  stands  simultaneously. 

Sheldon  Process. — See  page  384. 

Shell. — (i)  A  defect:  see  Pit;  (2)  a  casing;  (3)  in  cold  rolling  or 
drawing:  see  page  101;  in  crystallography:  see  page  126. 

Shelling. — (i)  A  defect:  see  Pit;  (2)  in  cold  rolling  or  drawing:  see 
page  10 1. 

Shelling  Out;  Shelly.— See  Pit. 

Sherard  Process;  Sherardizing.— See  page  371. 

Sherk  and  Rutter  Converter. — See  page  24. 

Sherman  Process. — See  pages  380  and  387. 

Shingling. — See  pages  177  and  377. 

Shock.— See  pages  330  and  333. 

Shock  Test. — See  page  481. 

Shop  Coat. — See  page  365. 

Shore  Layers. — In  the  freezing  of  alloys :  see  page  54. 

Shore  Pyroscope. — See  page  208. 

Shore  Scleroscope;  Test. — See  page  478. 

Short;  Shortness. — See  Brittleness. 

Short  Heat. — See  page  226. 

Short-tailed  Monkey.— See  Monkey. 

Short  Ton.— See  Ton. 

Shortening. — In  compression:  see  page  336. 

Shot  Iron. — Irregular  globules  of  cast  iron,  usually  about  ^  to  %"  in 
diameter,  produced  when  soine  of  the  contents  of  a  ladle  splash  on 
a  damp  floor,  or  produced  when  a  cupola  is  dumped. 

Shoulder. — (i)  Of  a  converter:  see  page  18;  (2)  of  a  roll:  see  page 

4°3- 

Shrink  Hole. — See  page  53. 
Shrinkage  Gage. — See  page  296. 
Shrinkage  Test.— See  page  484. 
Shrinking.— See  Cold  Working. 
Shrinking  Head. — See  page  56. 
Shudes. — See  page  432. 
Shut. — See  page  502. 
Shutter. — See  page  36. 
Sibbering. — See  page  376. 
Sibut  Process.— See  page  64. 


SIDE   BLOWN    CONVERTER— SILICO-MANGANESE    435 

Side  Blown  Converter. — See  page  18. 

Side  Fed  Tuyeres. — See  page  31. 

Side  Shears. — See  page  413. 

Siderite. — (i)  Kind  of  iron  ore:  see  page  244;  (2)  kind  of  meteorite: 

see  page  290. 

Siderography. — Engraving  on  iron  or  steel. 
Siderolite. — See  page  290. 

Siderology  ( Juptner) ;  Siderurgy. — Metallurgy  of  iron. 
Siegen  Process;  Raw  Steel  Finery  Process. — See  page  78. 
Siemens  Calorimeter. — See  page  201. 
Siemens  Calorimetric  Pyrometer. — See  page  207. 
Siemens  Electric  Furnace. — See  page  163. 
Siemens  Electric  Resistance  Pyrometer. — See  page  208. 
Siemens  Furnace. — See  pages  183  and  310. 
Siemens  Gas. — See  Producer. 

Siemens  and  Halske  Recording  Pyrometer. — See  page  210. 
Siemens-Martin  Process. — See  page  310. 
Siemens  Precipitation  Process. — See  page  146. 
Siemens  (C.  W.)  Process. — (i)  Of  casting:  see  page  64;  (2)  direct: 

see  page  146;  (3)  open  hearth:  see  page  310;  (4)  purification: 

see  page  387. 

Siemens  (F.)  Process. — See  page  146. 
Siemens  Regenerative  Furnace. — See  page  310. 
Siemens  Reversing  Process. — Regenerative  Heating. 
Siemens  Squeezer. — See  page  377. 
Siemens  Steel;  Siemens-Martin  Steel. — Open  hearth  steel,  either 

acid  or  basic. 
Silex  (obs.). — Silica. 
Silfrax. — See  page  398. 
Silhouette. — See  page  126. 
Silica;  Silica  Brick. — See  page  395. 
Silicate. — A  combination  of  silica  with  some  base. 
Siliceous  Clay. — See  page  396. 
Siliceous  Ore. — See  page  243. 
Siliceous  Rocks. — See  page  395. 
Silicide  of  Carbon. — See  page  398. 
Silicized  Carbon. — See  page  398. 
Silico-Calcium. — A  product  of  the  electric  furnace  intended  to  be 

used  as  a  deoxidizing  addition  for  steel;  an  analysis  shows: 

Silicon  66 .98  % 

Sulphur  tr. 

Phosphorus  o .  056 

Calcium 27.50 

Aluminum 2.31 

Iron 0.41 

Magnesium tr. 

Manganese  nil 

Moisture 0.13 

Silico-Ferrite. — See  page  272. 

Silico-Ferro-manganese;  Silico-manganese. — See  page  354. 


436       SILICO-M AN GANESE— SIMPLE  INDUCTION 

Silico-Manganese  Steels. — See  page  452. 

Silico-Spiegel;  Silicon  Spiegel. — See  page  354. 

Silicon.— Si;  at.  wt,  28;  melt,  pt,  1200°  C.  (2192°  F.);  sp.  gr., 
amorphous,  2.15,  crystalline,  2.34  to  2.49.  It  is  always  found 
combined  with  oxygen  as  silica  (sand)  or  a  silicate.  When 
pure  it  is  a  white  metal,  and,  depending  upon  the  method  of 
preparation,  may  be  amorphous  or  crystalline.  "From  dif- 
ferences that  have  been  discovered,  and  from  the  close  analogy 
that  exists  between  silicon  and  carbon,  it  was  at  one  time  believed 
that  three  allotropes  of  this  element  existed,  corresponding 
to  those  of  carbon.  Amorphous  silicon  was  considered  to 
represent  charcoal.  A  crystalline  substance  obtained  by  Wohler, 
by  heating  potassium  silico-fluoride  with  aluminum,  has  been 
regarded  as  corresponding  to  graphite,  and  called  graphitic 
silicon  (graphitoidal  silicon);  while  the  octahedral  crystals 
of  silicon  prepared  by  other  reactions  (Deville)  were  thought 
to  be  the  analogue  of  the  diamond;  and  this  substance  has 
therefore  been  called  diamond  silicon  or  admantine  silicon" 
(Newth).  Silicon  combines  with  iron  to  form  a  silicide  (iron 
silicide)  FeSi2.  It  is  always  a  constituent  of  pig  iron;  if  higher 
than  about  6%  it  is  called  ferro-silicon  <see  page  354)  in  which 
form  it  is  valuable  as  a  deoxidizer  (see  page  394).  In  ordinary 
steel  it  is  usually  under  about  0.030%;  in  steel  castings  it  is 
generally  under  about  0.25%;  while  for  certain  purposes  it 
may  go  as  high  as  1.00%.  It  is  now  recognized  that  it  has 
no  deleterious  influence  up  to  at  least  1.00%  and  probably 
higher,  and  has  only  a  slight  effect  in  the  amounts  usually 
met  with.  In  molten  pig  iron  it  lowers  the  saturation  point 
for  carbon,  and  during  cooling  tends  to  throw  it  out  as  graphite. 
For  influence  on  corrosion:  see  page  366. 

Silicon  Additions. — See  Recarburization. 

Silicon-Calcium  -Aluminum. — See  page  354. 

Silicon  Carbide. — See  page  398. 

Siliconeisen. — See  page  354. 

Silicon  Ore. — See  Codorus. 

Silicon  Steels. — See  page  452. 

Siliciuration. — See  page  66. 

Silit. — See  page  398. 

Silky  Fracture. — See  page  178. 

Sill. — The  bottom  of  the  door  of  a  reverberatory  furnace. 

Silocel  Brick. — See  page  396. 

Siloxicon. — A  trade  name  given  to  a  highly  refractory  compound  of 
silcon,  carbon,  and  oxygen,  having  the  formula  Si2C2O  produced 
in  the  electric  furnace. 

Silundum. — See  page  398. 

Silvery  Gray  Iron;  Silvery  Iron;  Pig. — See  page  343. 

Similarity. — Law  of:  see  page  473. 

Simple  Alloy.— See  Alloy. 

Simple  Axial  Stress. — See  page  332. 

Simple  Beam. — See  page  468. 

Simple  Cells. — See  page  121. 

Simple  Induction  Furnace. — See  page  153. 


SIMPLE  MATHEMATICAL  RATIO— SKEW  ROLLS     437 

Simple  Mathematical  Ratio. — Law  of  for  crystals:  see  page  120. 

Simple  Metals. — See  page  125. 

Simple  Microscope. — See  page  285. 

Simple  Overstrain. — See  page  282.- 

Simple  Radical. — See  page  87. 

Simple  Shear. — See  page  337. 

Simple  Slip. — See  page  283. 

Simple  Stress. — See  page  332. 

Simple  Twinning. — See  page  124. 

Simpson  Weld. — See  page  504. 

Singles. — Of  sheets:  page  430. 

Single  Acting  Hammer. — See  Hammer. 

Single  Blow  Test. — See  page  481. 

Single  Coil.— See  Coil. 

Single  Furnace. — See  page  376. 

Single  Level  Furnace. — See  page  312. 

Single  Melting  Process. — See  page  75. 

Single  Microscope. — See  page  285. 

Single  Mill. — See  page  430. 

Single  Puddling  Furnace. — See  page  376. 

Single  Refined  Iron. — See  page  378. 

Single  Rolled  Iron. — See  page  378. 

Single  Shear.— See  page  337. 

Single  Shear  Heat. — See  page  71. 

Single  Shear  Steel.— See  Shear  Steel. 

Single  Skip, — See  page  33. 

Single  Steel. — See  page  430. 

Single  Strand  (Strip)  Coil.— See  Coil. 

Sink  Hole. — See  page  53. 

Sinker. — See  page  509. 

Sinkhead. — See  pages  56  and  299. 

Sinking. — See  page  79. 

Sinking  Fire. — A  forge  in  which  wrought  iron  scrap  or  refined  pig  is 

partially  melted  or  welded  together  by  means  of  a  charcoal  fire 

and  a  blast  (Raymond). 
Smking  Head. — See  page  56. 
Sinking  a  Lump. — See  page  79. 

Suiter. — (i)  To  fuse:  see  page  45;  (2)  cinder:  see  Slag. 
Size  of  Crystals;  Grains. — See  pages  121  and  213. 
Size  of  a  Rolling  Mill. — See  page  410. 
Sizing. — See  Ore. 
Sizing  Rolls. — See  page  490. 
Skelp;  Skelper. — See  page  489. 
Skeletal  Crystal;  Skeleton  Crystal.— See  page  122. 
Skeller;  Skellering  (Yorkshire). — The  warp  sometimes  produced  in 

a  piece  of  steel  when  quenched;  also  for  castings  on  annealing. 
Skelp;  Skelper;  Skelping. — See  page  489. 
Skew  Back. — That  part  of  the  roof  of  a  furnace  at  which  the  spring 

of  the  arch  starts. 
Skew  Plate. — See  page  135. 
Skew  Rolls ;  Rollers. — A  series  of  rollers,  set  at  a  slight  angle  to  "the 

longitudinal  direction  of  the  table,  for  handling  bars  or  other 


438  SKIMMER— SLAG 

small  rolled  products;  the  effect  of  the  angle  is  to  throw  the 
pieces  to  one  side  where  they  are  assembled  against  a  guard. 

Skimmer. — See  page  36. 

Skin. — (i)  In  an  ingot,  the  layer  of  metal  between  the  blow- 
holes and  the  outside;  (2)  in  a  forged  or  rolled  piece,  the  thin 
outside  layer  which  has  a  very  fine  structure  due  to  the  work 
and  the  chilling  action  of  the  machine. 

Skin  Annealing. — See  page  232. 

Skin  Breakage.— See  Cold  Working. 

Skin  Dried.— See  page  298. 

Skin  Hardening. — See  page  69. 

Skip;  Skip  Bridge;  Skip  Charging. — See  page  33. 

Skull. — Sometimes  spelled  scull;  (i)  the  steel  or  cast  iron  which  has 
solidified  against  the  inside  surface  of  a  ladle,  or  to  remove  the 
same;  (2)  in  a  blast  furnace:  see  page  35. 

Skull  Breaker;  Cracker. — A  heavy  ball  or  piece  of  metal,  with  the 
necessary  appliances,  which  is  raised  and  dropped  on  a  skull  or 
other  large  piece  of  metal  to  reduce  it  to  a  size  convenient  for 
handling. 

Slab. — See  page  411. 

Slab  Ingot.— See  page  53. 

Slabbing  Mill. — See  page  413. 

Slack. — (i)  See  Coal;  (2)  of  lime:  see  page  396. 

Slag. — Also  called  cinder  or  sometimes  scoria;  the  molten  sub- 
stance, other  than  the  metal  under  treatment,  consisting  of  acid 
or  basic  oxides  which  may  be  composed  (a)  in  smelting,  operations, 
of  the  gangue  of  the  ore  combined  with  some  fluxing  material 
(usually  lime)  added  to  render  it  fusible  and  easily  separated 
from  the  metal,  and  also  to  effect  a  certain  amount  of  purification, 
or  (b)  in  purifying  processes,  of  substances  (usually  lime  and  iron- 
oxide)  introduced  for  the  purpose  of  effecting  or  assisting  in  the 
purification.  A  slag  which  is  infusible  or  pasty  is  sometimes 
called  a  dry  slag;  one  which  is  fusible  and  liquid,  a  wet  slag. 
A  scouring  cinder  is  one,  generally  high  in  oxide  of  iron,  which 
is  very  liquid  and  attacks  and  corrodes  the  lining  of  a  furnace. 
A  slag  is  acid  or  basic  depending  upon  whether  the  principal 
constituent  is  respectively  silica,  or  lime  or  oxide  of  iron.  A 
bastard  slag  is  the  name  sometimes  applied  (a)  to  a  slag  in  a 
basic  furnace  which  is  not  sufficiently  basic,  or  (b)  to  a  slag  in 
an  acid  furnace  to  which  lime  has  been  added  (usually  toward 
the  end  of  tlje  heat)  with  the  idea  of  effecting  a  slight  elimination 
of  phosphorus.  A  preliminary  slag  is  (a)  the  slag  existing 
shortly  after  the  commencement  of  a  refining  process,  or  (6) 
that  which  is  tapped  out  before  the  end  of  the  process:  in  blast 
furnace  work  this  is  termed  roughing  cinder  or  flush;  in  pud- 
dling, boilings.  A  final  slag  is  the  slag  existing  at  the  end  of 
a  process,  or  what  is  tapped  out  at  that  time,  usually  called 
tapping  slag;  in  puddling,  tappings  or  tap  cinder;  puddling 
furnace  cinder  is  rarely  called  mill  cinder  or  mill  tap.  Drop 
is  an  obsolete  name  for  the  slag  collected  at  ..the  bottom  of  the 
hearth  of  a  Catalan  forge,  or  puddling  furnace.  The  term 
reaction  slag  has  been  applied  to  that  found  in  steel  resulting 


SLAG-BEARING—SLAG  PROCESSES  439 

from  a  chemical  reaction  while  molten  as  distinguished  from  that 
found  in  the  furnace  (furnace  slag)  during  the  process,  particles 
of  which  may  be  mechanically  retained  in  the  metal  during 
solidification.  The  slag  expelled  under  a  hammer  from  a  ball  or 
lump  of  wrought  iron  after  drawing  from  the  furnace  is  called 
hammer  slag  or  forge  cinder.  In  England  blacksmith's  slag  is 
sometimes  called  hards.  The  slag  very  rich  in  oxides  of  iron 
formed  by  the  oxidation  of  the  iron  in  reheating  furnaces  is 
called  heating  furnace  cinder  or  flue  cinder.  Buckshot  cinder  is 
blast  furnace  slag  containing  small  particles  of  metallic  iron. 
Tarmac  (Eng.)  is  slag  treated  while  hot  with  molten  tar  or  pitch 
and  used  as  a  road-making  material. 

Slag-bearing. — Containing  slags,  as  wrought  iron. 

Slag  Bottom. — See  Lining. 

Slag  Bottom  Process. — See  page  78. 

Slag  Brick.— See  Slag  Cement. 

Slag  Cement. — (i)  Granulated  or  ground  blast  furnace  slag  mixed 
with  slaked  lime,  referred  to  specifically  as  blast  furnace  slag 
cement;  (2)  a  regular  Portland  cement  in  which  blast  furnace 
slag  is  used  as  the  base.  Greiner  gives  the  following  description 
of  the  manufacture  (/.  /.  6*  S.  Inst.,  1914,  i,  45+):  a  mixture  of 
75%  of  granulated  slag  and  25%  of  lime  is  fritted  in  the  kilns 
usually  employed  in  the  Portland  cement  industry;  by  these 
means  there  are  obtained  nodules,  or  semi-fused  agglomerates, 
possessing  a  special  molecular  texture  and  termed  clinker.  A 
mixture  of  70%  clinker  and  30%  granulated  slag,  finely  ground, 
yields  a  cement  of  superior  quality  known  in  Germany  as  Eisen- 
Portland,  and  accepted  during  the  last  five  years,  under  the  same 
category  as  Portland  cement,  by  public  administrations  and 
the  International  Sales  Syndicate.  The  granulated  slag  mixed 
with  a  small  percentage  of  slaked  lime  is  put  under  presses,  and 
slag  bricks  thus  formed,  and  heated  in  autoclaves  (pressure 
chambers)  under  steam  at  a  pressure  of  one  to  eight  atmos- 
pheres, acquire  a  remarkable  degree  of  hardness.  Uniformity  of 
shape  and  a  pleasing  appearance  create  a  demand  for  all  kinds  of 
masonry  work  which  they  render  drier  and  more  impervious  to 
moisture  than  ordinary  brick. 

Slag  Formation,  Zone  of. — See  page  36. 

Slag  Inclusion. — See  page  57. 

Slag  Ladle.— See  Ladle. 

Slagless. — Free  from  or  containing  only  accidental  traces,  as  steel 
produced  in  the  fluid  condition. 

Slag  Line. — In  the  crucible  process:  see  page  115;  (2)  in  the  open 
hearth  process:  see  page  311. 

Slag  Machine. — A  machine  for  handling  the  slag  from  a  blast  fur- 
nace. It  usually  consists  of  a  series  of  shallow  iron  pans  in  an 
endless  chain  on  which  the  slag  is  chilled  with  sprays  of  water, 
after  which  it  is  dumped  into  cars. 

Slag  Notch. — See  page  32. 

Slag  Pit.— See  page  312. 

Slag  Pocket. — See  page  311. 

Slag  Processes. — See  page  384. 


440  SLAG  SHORT— SNAKE 

Slag  Short,  Shortness.— See  Brittleness. 

Slag  Wool. — Also  called  mineral  wool;  it  is  a  downy  fibrous  sub- 
stance, somewhat  resembling  wool,  produced  by  blowing  a  jet 
of  steam  of  air  against  a  small  stream  of  molten  slag.  A  similar 
substance,  made  from  lime  and  silicious  rocks  melted  together,  is 
called  rock  wool. 

Slake. — See  page  396. 

Slaty  Fracture. — See  page  178. 

Slaviankoff  Process. — See  page  503. 

Slavianoff  Electric  Casting. — See  page  65. 

Sleazy  (Eng.). — Usually  referring  to  fabrics  but  sometimes  applied 
to  iron  or  steel  objects,  particularly  sheets,  which  are  weak  or 
lacking  in  body. 

Sledge. — See  Hammer. 

Sleeve  Brick.— See  Ladle. 

Slick  Angular  Method. — Of  rolling:  see  page  420. 

Slip. — (i)  Of  a  blast  furnace:  see  page  35;  (2)  of  metals:  see  page 
282. 

Slip  Band;  Theories. — See  page  282. 

Slip  Fracture. — See  page  179. 

Slip  Plane;  Slipping  Plane. — See  pages  123  and  282. 

Slitting  Mill;  Pass. — See  page  419. 

Sliver. — A  very  thin  piece  of  metal  rolled  into  the  surface  of  a 
piece  to  which  it  is  attached  by  only  one  end. 

Slopping. — See  page  21. 

Slow  Cement. — See  page  67. 

Slow  Combustion. — See  page  202. 

Slow  Pouring. — See  page  59. 

Slow  Test.— See  page  468. 

Sludge.— See  page  33. 

Small  Billet.— See  page  411. 

Small  Calorie. — See  page  199. 

Smelt. — To  extract  the  metal  or  metals  from  an  ore  in  a  furnace 
by  reduction,  usually  by  means  of  solid  carbonaceous  matter, 
such  as  coal,  coke,  or  charcoal,  whicty  also  supplies  the  necessary 
heat.  This  term  should  be  carefully  distinguished  from  melt, 
which  signifies  simple  fusion,  for  which  it  is  sometimes  incorrectly 
used. 

Smelter  Coke. — See  page  97. 

Smith -Casson  Process. — See  page  61. 

Smith  Coal;  Smithy  Coal.— See  Coal. 

Smith  (Wm.)  Process. — See  page  232. 

Smith's  (Angus)  Solution. — See  page  365. 

Smiths'  Tool  Temper.— See  Temper. 

Smithing  (Eng.). — See  Forging. 

Smithy  Slack  (obs.). — Hammer  scale. 

Smithy  Test  (Eng.).— See  page  476. 

Smoke. — See  page  202. 

Smoky  edged  Plate. — See  page  432. 

Smooth  Fracture. — See  page  178. 

Smyth  Process. — See  page  388. 

Snake. — See  Seam. 


SNARLING— SOLUTION  44 1 

Snarling. — See  page  476. 

Snelus  Process. — See  page  147. 

Snipping  (Eng.). — Chipping  off,  as  with  a  tool  struck  by  a  hammer. 

Snyder  Furnace. — See  page  163. 

Soaking;  Soaking  Furnace;  Soaking  Pit;  Soaking  Pit  Process. — 
Seepage  184. 

Sodium. — Na;  at.  wt.,  23;  melt,  pt,  97.6°  C.  (207.7°  F.);  sp.  gr., 
0.97.  It  is  never  found  in  nature  in  the  uncombined  state. 
It  is  a  soft  white  metal  readily  oxidized.  The  oxide  and  the 
carbonate  have  a  very  limited  application  as  a  flux,  but  prac- 
tically never  in  the  metallurgy  of  iron  and  steel. 

Sodium  Picrate. — As  an  etching  medium:  see  page  287. 

Soft  Annealing. — See  page  232. 

Soft  Blast.— Blast  which  is  weak  or  low  in  pressure. 

Soft  Centered  Steel.— See  page  64. 

Soft  Coal.— See  Coal. 

Soft  Coke. — See  page  97. 

Soft  Roll.— See  page  403. 

Soft  Solder. — See  page  505. 

Soft  Spot.— See  Hard  Spot. 

Soft  Steel. — See  page  455. 

Softener. — See  page  347. 

Softening  Point. — See  page  396. 

Soldering. — See  page  505. 

Sole. — (i)  The  hearth  of  a  furnace:  see  page  183;  (2)  the  bottom  or 
bottom  surface. 

Sole  Plate. — A  plate  placed  under  the  bottom  or  sole,  as  of  a 
furnace;  a  rail. 

Solid. — (i)  The  condition  of  being  solid  or  not  readily  mobile,  as 
contrasted  with  liquids  and  gases;  (2)  sound;  free  from  cavities, 
such  as  blowholes  or  pipe;*(3)  in  one  piece,  as  solid  steel  wheel; 
(4)  see  page  81. 

Solid  Cement. — See  pages  67  and  68. 

Solid  Contraction. — See  page  53. 

Solid  Ingots. — See  page  59. 

Solid  Solution  (adj.,  Solid  Solubility). — See  page  270. 

Solid  State.— See  page  81. 

Solidification. — See  pages  53  and  266. 

Solidification  Point. — See  page  201. 

Solidification  Range. — See  pages  54  and  267. 

Solidified  Solution. — See  page  270. 

Solidoid. — See  page  270. 

Solidus;  Solidus  Curve. — See  pages  268  and  270. 

Solubility  Curve. — See  Curve. 

Solute. — See  pages  83  and  below. 

Solution. — In  the  ordinary  sense  a  homogeneous  mixture  of  either 
a  gas,  a  liquid,  or  a  solid  wkh  a  liquid,  this  liquid  being  termed 
the  solvent  (Newth)  and  the  dissolved  substance  the  solute. 
A  saturated  solution  is  one  which  contains  the  maximum  amount 
of  a  given  substance  which  can  be  dissolved  under  the  given  condi- 
tions; it  is  supersaturated  when  there  is  more  in  solution  than  can 
normally  exist,  or,  in  other  words,  it  is  in  unstable  equilibrium. 


442       SOLUTION  PLANE— SPECIAL  HEAT  TREATMENT 

A  solubility  curve  is  a  diagram  showing  the  different  concentra- 
tions for  changes  in  temperature  and  (sometimes)  in  pressure. 
Solution  pressure  is  the  energy  with  which  molecules  seek  to 
leave  the  solid  state  and  go  into  solution.  The  coefficient  of 
distribution  is  the  proportion  of  a  third  substance  dissolved  by 
each  of  two  other  substances,  both  of  which  are  in  contact  with  it 
and  with  each  other.  Diffusion  is  the  tendency  of  a  solution  to 
mingle  with  one  more  dilute,  or  of  different  composition,  until 
the  mixture  is  homogeneous  or  of  uniform  composition  through- 
out; this  is  the  reverse  of  segregation.  Osmose  is  the  diffusion 
of  a  crystalline  body  in  solution,  or  of  two  different  solutions, 
through  a  porous  membrane  or  diaphragm.  The  passage  from 
the  side  on  which  it  was  originally  is  called  exosmose;  that  to  the 
other  side,  endosmose.  The  pressure  exerted  thereby  on  the 
membrane  is  known  as  osmotic  pressure.  A  substance  which 
will  not  so  diffuse  is  called  a  colloid. 

Solution  Plane. — See  page  127. 

Solution  Pressure. — See  Solution. 

Solution  Theory. — Of  hardening:  see  page  279. 

Solvent.— See  Solution. 

Solvite. — See  page  273. 

Sonim. — See  page  279. 

Sonority  Test. — See  page  483. 

Sorbite. — (i)  In  metallography:  see  page  276;  (2)  a  name  formerly 
given  to  ruby  and  blue  crystals  found  by  Sorby,  and  only  in 
certain  cast  iron,  which  were  shown  to  be  nitride  of  titanium. 

Sorbitic  Pearlite. — See  page  273. 

Sorbitic  Steel. — Steel  containing  a  large  proportion  of  sorbite. 

Sorbitism. — See  page  277. 

Sorby's  Reagent. — For  etching:  see  page  287. 

Sorting. — See  Ore.  •• 

Sound. — Free  from  defects,  particularly  pipes  and  blowholes. 

Sound  Steel. — See  page  59. 

South  Wales  (Welsh)  Process. — See  page  79. 

Sow;  Sow  Metal. — See  page  342. 

Space -Lattice;  Theory. — See  page  121. 

Spall. — (i)  Of  bricks,  etc.,  when  they  are  easily  abraded;  (2)  of  car 
wheels,  shelling  out:  see  page  357;  (3)  of  cast  iron  rolls,  when 
particles  crack  or  flake  out  of  the  surface. 

Spangle.— See  page  431. 

Spanner. — See  page  406. 

Spar. — Fluorspar:  see  Flux. 

Spark  Test. — See  page  484. 

Sparry  Ore. — See  page  244. 

Spathic;  Spathose;  Spathous.— Having  an  even  lamellar  or  flatly 
foliated  structure  (Cent.  Diet.). 

Spathic  Carbonate;  Iron  Ore;  Ore.— See  page  244. 

Spawl.— See  Spall. 

Special  Additions.— See  Recarburization. 

Special  Cast  Iron. — See  page  351. 

Special  Ferro-Silicon. — See  page  354. 

Special  Heat  Treatment. — See  page  212. 


SPECIAL  HIGH  SILICON— SPECIAL  STEELS       443 

Special  High  Silicon  Iron. — See  page  354. 

Special  Long  Ton.— See  Ton. 

Special  Low  Phos.;  Low  Phosphorus  Pig. — See  page  346. 

Special  Open  Hearth  Processes. — See  page  315. 

Special  Steels. — Also  called  alloy  steels,  or  combination  steels, 
and  rarely,  alloyed  carbon  iron,  are  steels  which  owe  their 
properties  chiefly  to  the  presence  of  an  element  or  elements 
other  than  carbon  (I.A.T.M.).  If  the  carbon  is  over  about  2% 
they  are  usually  termed  ferro-alloys  (?.».,  page  351).  The  ele- 
ments (alloy  elements)  principally  concerned  are  nickel,  chro- 
mium, vanadium,  tungsten,  molybdenum,  manganese  (over 
about  7%),  and  silicon  (over  about  0.5%).  In  contradistinc- 
tion to  the  above,  steel  which  owes  its  properties  chiefly  to  vari- 
ous percentages  of  carbon  is  known  as  ordinary  steel  or  carbon 
steel.  In  a  general  sense  carbon  steels  which  are  prepared  for 
some  specific  purpose  are  sometimes  spoken  of  as  special  steels, 
but  this  is  not  the  customary  practice.  In  this  class  might  be 
included  what  Longmuir  calls  high  tension  steels,  a  term  which 
he  employs  to  cover  endurance  to  reversal  of  stresses  as  well  as 
actual  high  tensile  strength;  in  other  words  steels  possessing  high 
resistance  to  service  conditions  (more  properly  high  resistance 
steels)  which  are  not  usually  limited  to  tensile  stresses.  Quality 
steels  (Eng.)  are  those  of  high  quality  intended  for  special  pur- 
poses, and  not  necessarily  containing  special  elements.  Ternary 
steels  are  those  which  consist  chiefly  of  iron,  carbon,  and  one 
other  special  element;  quaternary  steels,  of  iron,  carbon,  and  two 
other  special  elements. 

Guillet's  Theory  of  Ternary  Steels.— Sauveur  explains  this  as 
follows  (Metallography,  326-7):  "Too  rigorous  an  application  of 
the  theory,  however,  should  not  be  insisted  upon  for  there  are 
some  facts  not  yet  satisfactorily  explained  by  it.  Its  use,  never- 
theless, will  be  found  an  invaluable  guide  in  directing  researches 
dealing  with  the  manufacture  and  the  application  of  these 
steels. 

"Guillet's  theory  of  the  structure  and  properties  of  ternary 
steels  may  be  briefly  formulated  by  a  few  propositions.  It  is 
also  represented  graphically  in  Fig.  59. 

"  (i)  On  the  introduction  of  a  special  element  in  carbon  steel  the 
latter  remains  at  first  pearlitic,  but  as  the  proportion  of  special 
element  increases,  the  carbon  remaining  constant,  it  becomes 
first  martensitic  and  then  austeni tic  (polyhedral),  as  shown  graph- 
ically in  Fig.  59,  and  sometimes  called  cementitic  (carbide  steel) 
as  later  explained. 

"(2)  By  increasing  the  amount  of  carbon  present  in  a  special 
steel,  the  proportion  of  the  special  element  being  kept  constant,  it 
is  generally  converted  from  a  pearlitic  into  a  martensitic  condi- 
tion or,  if  already  martensitic,  into  an  austenitic   condition. 
"(3)  The  greater  the  amount  of  carbon  the  smaller  the  pro- 
portion of  the  special  element  needed  to  cause  a  structural 
transformation,  as  for  instance  pearlite  into  martensite  or  marten- 
site  into  austenite.    This  is  indicated  in  Fig.  59. 
"  (4)  The  greater  the  amount  of  the  special  element  the  smaller 


444 


SPECIAL  STEELS 


the  proportion  of  carbon  needed  to  cause  a  structural  transforma- 
tion. This  is  also 'shown  in  Fig.  59. 

"  (5)  No  very  sharp  lines  of  demarcation  are  observed  between 
the  different  types  of  structures  mentioned  in  the  preceding 
propositions,  relatively  wide  ranges  of  composition  existing,  on 
the  contrary,  in  which  the  steel  may  be  partly  pearlitic  and  partly 
martensitic  or  partly  martensitic  and  partly  austenitic,  etc. 
These  transition  ranges  are  indicated  by  shaded  areas  in  the 
diagram  of  Fig.  59.  Greater  refinement  in  the  construction  of 
this  diagram  would  undoubtedly  lead  to  the  introduction  of  a 
troostitic  zone  between  the  pearlite  and  martensite  areas  and 
possibly  also  of  a  sorbitic  zone  between  pearlite  and  troostite. 

"To  sum  up,  constituents  may  be  formed  during  the  slow 
cooling  of  many  alloy  steels  which  in  carbon  steels  can  only  be 
produced  by  very  rapid  cooling  through  the  critical  range. 


.6  .8  1.0 

Per  cent    Carbon 


PIG.   59. — Ternary  steels. — (Sauveur} . 


Carbon  steels,  moreover,  even  after  very  rapid  cooling  cannot 
be  retained  wholly  in  an  austenitic  condition  while  several 
special  steels  remain  austenitic  after  slow  cooling  It  is  evident 
from  the  above  and  from  the  diagram  that  in  order  to  produce  a 
certain  structure,  (i)  the  proportion  of  carbon  may^  be  kept 
constant  while  the  proportion  of  the  special  element  is  increased 
until  the  desired  structure  is  obtained,  or  (2)  the  proportion  of 
the  special  element  may  be  kept  constant  and  the  proportion 
of  carbon  increased,  or  (3)  both  the  proportion  of  carbon  and  of 
the  special  element  may  be  increased  when  the  desired  structure 
will  be  obtained  more  quickly." 

Constitution  of  Special  Steels. — As  stated  in  Guillet's  theory 
the  normal  condition  of  special  steels  at  ordinary  temperatures 
is  dependent  primarily  upon  the  nature  and  amount  of  the  special 
element  or  elements  in  conjunction  with  the  percentage  of  carbon 


SPECIAL  STEELS  445 

and  the  heat  treatment.     Based  on  ordinary  or  slow  cooling  a 
classification  may  be  made  into: 

1.  Pearlitic  steels:  Similar  to  carbon  steels,  and,  as  a  rule, 
relatively  low  in  special  elements.     "In  these  steels  the  special 
element  may  (i)  be  dissolved  in  the  ferrite  forming  with  it  a  solid 
solution,  (2)  be  combined  with  carbon  in  cementite  as  a  double 
carbide  of  iron  and  the  special  element,  or  (3)  be  partly  dissolved 
in   ferrite   and   partly   combined   with   carbon.     According   to 
Guillet  nickel  and  silicon,  for  instance,  are  entirely  dissolved  in 
ferrite,  while  manganese,  chromium,  tungsten,  vanadium,  and 
molybdenum  are  partly  held  in  solution  by  ferrite  and  partly 
present  in  cementite  as  double  carbides"  (Sauveur,  Metallography, 
331).     "  Guillet  writes  that  pearlitic  special  steels  may  be  divided 
into  (i)  those  that  are  not  very  sensitive  to  annealing,  namely, 
nickel  and  silicon  steels,  and  (2)  those  that  are  very  sensitive  to 
annealing,  namely,  manganese,  chrome,  vanadium,  tungsten,  and 
molybdenum  steels.     It  should  be  noted  that  in  the  first  group 
the  special  elements  are  supposed  to  be  entirely  dissolved  in  the 
iron,  while  in  the  second  group  they  are  partly  dissolved  and 
partly  present  as  carbides"  (Sauveur,  ibid.,  333-4). 

2.  Martensitic  steels:  With  a  higher  combination  of  special 
elements  and  carbon  than  the  preceding;  except  by  very  slow 
cooling  they  are  hard,  and  are  not  affected  by  ordinary  tempering 
operations. 

3.  Austenitic  (polyhedral)  steels :  With  a  still  higher  combina- 
tion of  the  special  elements  and  carbon.     They  are  non -magnetic 
as,  for  example,  in  the  case  of  n  %  manganese  steel  or  25  % 
nickel  steel.     Sauveur  points  out  (ibid.,  334)  that  air   cooling 
may  be  required  to  produce  truly  austenitic  steels;  with  slower 
cooling   particles    of  carbide  may  separate  out,  and  to    cause 
reabsorption    the    steel    is    reheated    to    a    high    temperature 
followed  by  oil  or  water    quenching,  the   latter  termed  water 
toughening. 

4.  Cementitic   (carbide)  steels:  "Some  special  elements  on 
being  introduced  in  increasing  proportions  fail  to  convert  the 
metal  into  austenite,  free  particles  of  a  double  carbide  of  iron  and 
the  special  element  being  formed  instead  and  embedded  in  a 
martensitic,  troostitic,  sorbitic,  or  pearlitic  matrix.     Guillet  calls 
these    carbide   steels.     Such   elements  as  chromium,  tungsten, 
molybdenum,  and  vanadium  when  present  in  sufficient  quantity 
produce  cementitic  steels"  (Sauveur,  ibid.,  333). 

Special  elements  were  first  used  in  the  manufacture  of  steel 
for  machine  tools  (tool  steel),  which  was  then  called  special 
tool  steel  to  distinguish  it  from  the  ordinary  tool  steel  or  carbon 
tool  steel  formerly  made  exclusively.  Mushet  found  that 
a  steel  containing  about  1.50% of  carbon  and  5  to  8%  of  tungsten 
(a)  would  be  rendered  sufficiently  hard  by  simple  cooling  in  air 
(sometimes  an  air  blast  is  employed)  and  (b)  that  the  edge  or 
temper  of  such  a  tool  would  remain  practically  intact  at  a  temper- 
ature approaching  a  visible  red,  and  as  a  result  the  tool  would 
take  a  faster  or  a  heavier  cut.  For  these  reasons  such  steels  have 
been  denominated  Mushet  steel,  air-hardening  steel,  air- 


446  SPECIAL  STEELS 

quenched  steel,  self-hardening  steel,  high  speed  steel,  quick 
speed  steel,  or  rapid  tool  steel  (rarely  natural  steel). 

Taylor  and  White  experimented  with  tool  steels  to  obtain 
greater  efficiency,  and  the  method  of  treatment  which  they 
developed  (Taylor-White  process)  improves  nearly  all  kinds 
of  special  tool  steel.  Steel  so  treated  is  sometimes  termed 
Taylor-White  steel,  high  heat  tools,  or  modern  high  speed 
tools,  but  as  the  method  of  treatment  is  the  principal  factor, 
these  gentlemen  object  to  the  name  new  tool  steel  as  being 
misleading.  The  proces  consists  of  two  steps: 

1.  The  first  or  high  heat  treatment: 

(a)  heating  slowly  to  1500°  F.  (816°  C.); 
(6)  heating  rapidly  from  that  temperature  to  just  below 
the  melting  point; 

(c)  cooling  rapidly  to  below  1550°  F.  (843°  C.);  and 

(d)  cooling  either  rapidly  or  slowly  from  that  point  to 
the  temperature  of  the  air. 

2.  The  second  or  low  heat  treatment: 

(e)  heating   to   a   temperature   below  1240°  F.  (671°  C.), 
preferably  to  1150°  F.  (621°  C.),  for  about  5  minutes; 
and 

(f)  cooling  either  rapidly  or  slowly  to  the  temperature  of 
the  air.     The  second  treatment  may  also  be  produced 
by  running  the  tool  hot,  and  then  cooling  it  down. 
Between  1550°  and  1700°  F.  (843°  and  927°  C.)  they 
term   the  breaking   down   temperature,   as   ordinary 
tool  steel,  if  heated   within   this  range,  is  seriously 
injured  or  broken  down  in  its  cutting  speed.    Red 
hardness  is  the  name  they  give  to  the  property  of 
a  tool  when  it  maintains  its  cutting  edge  after  its 
nose  is  red  hot,  obtained  with  chrome-tungsten  steels 
(containing  not  less  than  0.5  %  of  chromium  and  i  % 
of  tungsten  or  its  equivalent)  by  heating  them  close 
to    their    melting   point.     They   have   published    the 
following  representative   analyses  (the  range  in  com- 
position for  many  self-hardening  steels  was  commu- 
nicated to  Howe  by  J.  A.  Matthews) : 

Mushet  Original    Best  Modern 
Jessop         Self-      Taylor-      High  Speed         Range 
Harding    White  1906 

Tungsten   5 .441  8.00  18.91       3.44^24.00 

Chromium...  0.207  0.308  3.80  5-47       o.ooto    6.00 

Carbon 1.047  *«5o  1.85  0.67       0.40  to    2.19 

Manganese..  0.189  1.578  0.30          o.n       

Vanadium o .  29       

Silicon 0.206  1.044  o-J5  o-°43     0.21  to    3.00 

Phosphorus..  0.017  0.025         

Sulphur 0.017  0.030         

E.  K.  Hammond  states  that  the  following  is  representative  of  the 
composition  of  the  early  Mushet  steel:  tungsten,  9.0%;  manga- 
nese, 2.5%;  carbon,  1.85%. 


SPECIAL  STEELS  447 

In  the  paper  on  "The  Effect  of  Chromium  and  Tungsten  upon 
the  Hardening  and  Tempering  of  High-Speed  Tool  Steel" 
(J.I.  6*5.7.,  1915,  ii,  29,  30),  Ed  wards  and  Kikkawa  reached  the 
following  conclusions: 

"i.  The  first  effect  of  tempering  hardened  high-speed  steels 
it  to  make  them  softer,  but  when  they  are  tempered  at  higher 
temperatures  they  again  become  harder,  and  after  heating  at  or 
about  614°  C.  (1137°  F.)  they  are  much  harder  than  in  the  initial 
air-quenched  state.  There  can  be  no  doubt  that  this  secondary 
hardening  is  the  cause  of  the  improved  cutting  powers  of  a  tool, 
which  Mr.  Taylor  found  was  brought  about  by  a  secondary  low 
heating  to  about  620°  C. 

"2.  Chromium  in  conjunction  with  carbon  is  the  cause  of  the 
great  hardness  of  hardened  high-speed  steels,  and  further,  it 
materially  lowers  the  temperature  at  which  these  steels  can  be 
air-hardened. 

"3.  In  the  absence  of  chromium,  tungsten  raises  the  tempera- 
ture at  which  tempering  or  annealing  begins,  and  in  the  presence 
of  chromium  it  increases  the  intensity  of  the  secondary  hardening, 
and  raises  the  tempering  temperature. 

"4.  Tungsten  steel  containing  18.0%  of  tungsten  and  0.63% 
of  carbon  can  be  air-hardened  only  by  rapid  air-quenching  from 
temperatures  above  1050°  C.  (1920°  F.). 

"5.  When  high-speed  steels  are  hardened  at  low  temperatures, 
say  1050°  C.,  the  tempering  properties  approximate  to  those  of  a 
pure  chromium  steel,  by  softening  at  a  low  temperature,  and 
developing  little  or  no  secondary  hardening.  This  is  due  to  the 
tungsten  being  undissolved  and  remaining  inactive. 

"6.  The  maximum  resistance  to  tempering  and  the  greatest  de- 
gree of  secondary  hardening  can  only  be  obtained  by  getting  the 
tungsten  into  solution,  and  with  modern  high-speed  steels  this  is 
not  complete  until  a  temperature  of  about  1350°  C.  (2460°  F.) 
is  reached. 

"7.  Specific  gravity  determinations  seem  to  indicate  that  there 
is  a  direct  connection  between  the  hardness  and  volume  of  these 
steels.  On  tempering,  an  increase  of  hardness  is  accompanied  by 
an  increase  in  volume." 

By  secondary  hardening,  referred  to  above,  is  meant  that 
resulting  from  the  reheating  or  tempering  of  high-speed  steels 
after  a  preliminary  or  initial  hardening,  which  in  contradistinction 
would  also  be  termed  primary  hardening.  Edwards  has  also 
employed  the  term  critical  cooling  velocity  to  indicate  the  rate  of 
cooling  which  must  be  maintained  if  self-hardening  is  to  result. 
In  connection  particularly  with  tungsten  steels  it  has  been  found 
that  the  higher  the  temperature  for  the  primary  treatment  the 
lower  would  be  subsequently  the  Aci  point;  this  has  been  termed 
the  lowering  temperature. 

The  following  is  an  abstract  (/.  7.  &•  S.  I.,  1915,  i,  605  taken 
from  Gassier' s  Eng.  Monthly):  "The  high-speed  steels  of  the 
present  day  are  combinations  of  iron  and  carbon  with  tungsten 
and  chromium;  molybdenum  and  chromium;  tungsten,  chromium, 
and  vanadium j  tungsten,  molybdenum,  chromium,  and  rana- 


448  SPECIAL  STEELS 

dium.  The  control  of  the  carbon  limits  is  a  very  important 
matter.  The  best  results  are  obtained  from  steels  containing 
0.5  to  0.7%  of  carbon.  Higher  percentages  are  not  desirable, 
because  great  difficulty  is  experienced  in  forging  the  steel. 
With  from  9  to  16%  of  tungsten  and  in  conjunction  with  chro- 
mium the  nature  of  the  steel  becomes  very  brittle,  but  at  the 
same  time  the  cutting  efficiency  is  greatly  increased.  Sixteen 
percent  of  tungsten  appears  to  give  maximum  hardness.  The 
presence  of  chromium  in  high-speed  steel  varies  from  i  to  6%. 
While  a  large  percentage  of  tungsten  is  necessary  in  a  good  steel, 
it  has  been  found  that  as  low  as  5  %  of  molybdenum  will  make 
an  excellent  steel.  Molybdenum  steels  do  not  require  such  a 
high  temperature  in  hardening  as  do  the  tungsten  steels.  The 
presence  of  i%  of  vanadium  in  a  high-speed  steel,  containing 
at  least  18%  of  tungsten,  enables  such  a  steel  to  be  quenched 
from  a  white  heat  in  water  without  cracking,  and  this  fact  led 
to  the  recent  production  of  water-hardening  high-speed  steels ; 
but  it  must  be  borne  in  mind  that  the  percentage  of  carbon 
must  not  exceed  0.6%,  otherwise  there  is  danger  of  cracking 
in  the  operation  of  hardening." 

In  regard  to  the  effect  of  heat  treatment  on  density  of  alloy 
steels  the  same  abstract  as  already  quoted  from  (see  Heat 
Treatment,  page  224)  states:  "In  alloy  steels  the  difference 
in  density  as  between  water-hardened  and  oil-hardened  steels 
is  not  nearly  so  great  as  in  the  case  of  ordinary  carbon  steels. 
Quenched  alloy  steels  show  no  maximum  at  430°  C.  (805°  F.), 
but  from  that  temperature  upwards  the  density  increases  con- 
tinually. Eutectoid  steels  tend  more  than  others  to  develop 
hardening  cracks,  on  account  of  their  greater  volume  changes 
during  quenching.  Bars  increase  in  length  according  to.  the 
carbon  content,  and  the  increase  is  proportional  to  the  length 
of  the  bar.  When  quenched  from  960°  C.  (1760°  F.)  several  of 
the  special  steels  always  gave  hardening  cracks,  so  that  the 
specific  gravity  could  not  be  determined.  The  nickel  and  chro- 
mium steels  show  a  smaller  increase  in  volume  with  quenching 
than  plain  steels  of  the  same  carbon  content.  This  is  also 
true  of  the  manganese  steels,  although  not  to  so  great  an  extent, 
while  the  chromium-nickel  steels  show  a  proportionally  great 
change  of  volume.  Although  these  results  do  not  apply  to  all 
special  steels,  yet  it  is  certain  that  through  suitable  special 
additions  the  change  in  volume  due  to  quenching  can  be  greatly 
reduced.  The  author  considers  that  the  change  in  volume 
brought  about  by  quenching  steel  is  only  small  if  the  quenching 
temperature  be  within  a  limit  close  to  the  critical  temperature. 
Very  great  changes  in  volume  are  brought  about  if  this  limit  is 
even  slightly  exceeded." 

The  special  steels  in  common  use  contain  one  or  more  of  the 
elements  (in  addition  to  carbon  and  manganese)  nickel,  chrom- 
'ium,  silicon,  and  vanadium.  With  the  exception  of  nickel  steel 
(for  certain  structural  purposes,  such  as  bridges)  they  are  usually 
given  a  special  heat  treatment  to  develop  as  far  as  possible 
the  properties  which  warrant  their  extra  cost.  The  following 


SPECIAL  STEELS 


449 


V 

H& 


• 

S 

0                                        O 

* 

.H-a 

IO 

a 

| 

•S  8 

%% 

10    O     O                         00     O 

<J 

> 

0                                        0 

jk^ 

0                                        0       • 

?  ?!         ? 

o 

c 

=1 

ro    O     0                         O 

o                           o 

&s 

0                    V«             IH 

0           -o       »S 

* 

|g 

???§§§§ 

%0     0-     ^-g     M 

ro 

o            £       £ 

65 

IO                               IO             IO 

to 

l^                      cs          O\ 

w 

1 

1u 

loo        T        1 

"M 

10     •      •         10         o 

3 

IO 

rfr    o     0            t-          vO 
O                            NO 

Q* 

_o 

N 

H 

'S 

i 

6? 

S                                ON 

s 

§ 

IO 

Q 

1 

o 

fO    O     O            10           §\ 

^ 

O                                   MO 

g5 

O                          0           to     ' 

o 

00                              IO            t- 

10 

1O 

O 

O       ^t     ^                M                 O 

i  °  °       JL        ' 

0 

O                          O           to 

to    O     O            0            •* 

o 

0                                   MO 

M 

3 

00                          V 

o   "i-  •*  c   o 

1      O    O    3    O 

s 

10  o   o   o   n 

o            & 

0 

hj 

oo 

^ 

, 

c 

3 

2>  o   o 

o 

1 

1     '; 

1 

5 

§ 

!  ^  I          ^ 

U 

•   w  ^         !               r 

M 

'     3  "'***"*•                  C 

1 

8  S  §      ;     g'  S- 

<U 

S 

S  2  ^"              -2^ 

1^1    3    l^ 

Jj-3      a      .S  S 

S  £  OT         ^         0  > 

450  SPECIAL  STEELS 

table  taken  from  the  specifications  for  forging  billets  of  the 
A.  S.  T.  M.  will  serve  to  illustrate  the  types  and  grades  (for 
carbon  as  well  as  alloy  steels)  commonly  used  for  special  f orgings 
of  any  size  (see  preceding  page). 

Carbon  Ranges  for  the  Various  Grades  for  Carbon  and 
Alloy  Steel 

Carbon  Steel— Type  A.      Alloy  Steel— Types  B  to  H,  Incl. 

Grade                           Carbon,  %  Grade                        Carbon,  % 

i 0.05-0.15     ii I..  0.10-0.20 

2 0.15-0.25     12 0.15-0.25 

3 0.20-0.30     13 0.20-0.30 

4 o . 25-0 .40     14 o . 25-0 . 38 

5 0.30-0.45     15 0.30-0.43 

6 0.35-0.50     1 6 0.35-0.50 

7 0.40-0.55     17 0.45-0.60 

8 o . 45-0 . 60 

NOTE  i . — When  the  steel  is  to  be  used  for  case-hardening  pur- 
poses, the  manganese  should  be  specified  not  to  exceed  0.50%. 
When  the  minimum  carbon  specified  is  0.35  %  or  over,  the  man- 
ganese range  may  be  specified  0.30-0.60%. 

NOTE  2.— In  selecting  billets  for  making  f  orgings  of  Classes  K, 
L  and  M,  as  defined  in  the  Standard  Specifications  for  Carbon- 
steel  and  Alloy-steel  Forgings  (Serial  Designation:  A  18)  of  the 
American  Society  for  Testing  Materials,  it  is  suggested  that  the 
use  of  steel  with  a  relatively  high  carbon  content  will  permit  the 
use  of  a  high  drawback  temperature  and  thus  put  the  steel  in  its 
best  physical  condition  for  service,  shock  and  similar  conditions. 

Tungsten  steels  (rarely  called  wolfram  steels),  as  now  made 
usually  contain  (Howe)  from  5  to  10%  (and  sometimes  even 
24%)  of  tungsten,  and  from  0.4  to  2%  of  carbon.  Tungsten- 
chrome  steels,  as  used  for  cutting  tools,  have  been  discussed 
above.  There  is  another  class,  known  as  magnet  steels  (mag- 
netic steels),  which  is  used  for  permanent  magnets  owing  to  its 
high  retentivity;  these  contain  (Rosenhain)  tungsten  about  7  % 
and  chromium  up  to  0.5%.  They  are  usually  quenched  in  oil 
or  water  to  render  them  as  hard  as  possible  as  this  is  necessary 
for  the  purpose  (magnetic  hardness).  Tungsten  probably 
goes  into  solution  as  the  tungsten  iron  compound  Fe3W;  in  the 
undissolved  form  it  may  exist  as  Fe2W  which  was  isolated  by 
Arnold  and  Read. 

Molybdenum  steels  are"  somewhat  similar  in  their  properties 
to  tungsten  steels,  and  apparently  i  %  of  molybdenum  is  equi- 
valent to  2%  of  tungsten  (Howe). 

Nickel  steels  (when  no  other  special  elements  are  present) 
ordinarily  contain  from  3  to  4  %  (usually  not  over  5  %)  of  nickel, 
from  o.io  to  0.50%  of  carbon,  and  about  0.30  to  0.80%  of 
manganese.  This  amount  of  nickel  renders  the  steel  much 
tougher  and  stiff er;  it  also  raises  the  ultimate  strength  and  the 
elastic  limit,  the  latter  to  a  greater  extent  than  the  former,  and 


SPECIAL  STEELS  451 

this  with  an  increase  in  the  ductility,  the  composition  other- 
wise, and  the  treatment,  remaining  the  same.  The  3  to  3^% 
grade  has  been  used  to  a  considerable  extent  for  structural  work, 
particularly  bridges,  of  which  some  of  the  most  important 
have  been  made  partly  or  almost  entirely  of  this  material. 
With  less  than  3%  nickel  the  principal  application  has  been 
for  case-hardening  purposes.  Nickel  steel,  containing  about 
36%  of  nickel,  patented  under  the  name  invar  (Guillaume's 
invar)  has  a  lower  coefficient  of  expansion  than  any  other  metal 
or  alloy  known  and,  in  consequence,  is  largely  employed  for 
instruments  of  precision.  Another  patented  alloy,  termed 
platinite,  contains  about  46  %  of  nickel,  and  at  ordinary 
temperatures  has  the  same  coefficient  of  expansion  as  glass 
(and  platinum),  and  for  this  reason  is  used  as  a  substitute  for 
platinum  in  the  manufacture  of  incandescent  lamps.  Types  of 
nickel-chrome  steels  are  shown  in  table  on  page  449.  Special 
types  of  nickel  and  particularly  nickel-chrome  steel  are  used  in 
the  manufacture  of  armor  plate  and  armor-piercing  projectiles. 

Chrome  steel  or  chromium  steel,  "which  usually  contains 
about  2%  of  chromium  and  0.80  to  2%  of  carbon,  owes  its 
value  to  combining,  when  in  the  hardened  or  suddenly  cooled 
state,  intense  hardness  with  a  high  elastic  limit,  so  that  it  is 
neither  deformed  permanently  nor  cracked  by  extremely  violent 
shocks.  For  this  reason  it  is  the  material  generally  if  not 
always  used  for  armor-piercing  projectiles.  It  is  much  used 
also  for  certain  rock-crushing  machinery  and  for  safes.  These 
last  are  made  of  alternate  layers,  usually  five  in  number,  of 
chrome  steel  and  wrought  iron,  welded  together,  and  then 
cooled  suddenly  so  as  to  harden  the  chrome  steel.  The  hard- 
ness of  the  hardened  chrome  steel  resists  the  burglar's  drill, 
and  the  ductility  of  the  wrought  iron  the  blows  of  his  hammer" 
(Howe).  More  recently  types  containing  a  lower  chrome 
content  have  received  wide  adoption  both  for  plain  chrome  steel 
and  in  combination  with  nickel  or  vanadium  (nickel-chrome  or 
chrome -nickel,  and  chrome-vanadium  steels — see  table,  page 
449).  Under  the  trade  name  crucia  steel  a  type  containing 
about  0.20  to  0.50%  chrome,  the  same  amount  of  manganese, 
and  about  0.80  to  1.00%  carbon  has  been  considerably  used 
for  certain  automobile  springs.  A  recent  patented  alloy,  called 
stainless  steel,  has  been  introduced  for  articles  of  cutlery 
(especially  for  fruit)  and  for  rifle  and  gun  barrels  owing  to  its 
almost  complete  freedom  from  ordinary  corrosion;  it  contains 
about  10  to  15%  of  chrome  and  carbon  less  than  about  0.50%. 
An  Austrian  steel  called  non-corro,  used  for  the  same  purposes, 
is  probably  of  somewhat  similar  composition.  Chrome  steel 
is  rarely  referred  to  as  chromated  steel. 

Manganese  steel  (Hadfield's  manganese  steel,  austenitic 
manganese  steel)  contains  about  12%  of  manganese  and  1.25% 
of  carbon  (the  manganese  is  usually  between  about  11  and  14%) 
and  was  discovered  by  Hadfield  in  1883;  in  1887  he  called  it 
self -hardening  steel.  Owing  to  its  great  hardness  it  is  ordinarily 
cast  nearly  to  shape  and  then  finished  by  grinding;  it  has  been 


452  SPECIAL  STEELS 

successfully  rolled  into  rails.  As  cast  or  otherwise  produced 
(with  relatively  slow  cooling)  it  is  extremely  brittle  and  to  remove 
this  it  is  heated  to  a  fairly  high  temperature  (about  1000°  C.- 
1830°  F.)  and  quenched  in  water.  This  has  the  effect  of  render- 
ing it  tough  and  ductile  without  materially  altering  its  hardness 
(tough  hardness),  and  for  this  reason  the  water  treatment 
is  known  as  water  toughening.  In  contradistinction  the  brittle- 
ness  allied  with  hardness  which  would  be  produced  in  an  ordinary 
steel  equally  high  in  carbon  has  been  called  brittle  hardness. 
Treated  manganese  steel  after  treatment  has  a  tensile  strength 
of  about  54  to  63  tons  (about  120,000  to  141,000  pounds)  per 
square  inch,  and  an  elongation  of  30  to  50%;  the  stretch  is  nearly 
uniform  throughout  the  length  tested  as  very  little  necking 
occurs.  The  Brinell  hardness  number  is  about  200,  whereas, 
without  such  high  manganese,  ordinary  carbon  steel  would  have 
a  hardness  number  of  about  600  to  800.  By  heating  sufficiently 
long,  up  to  700°  C.  (1290°  F.),  it  can  be  made  more  or  less 
magnetic;  the  best  temperature  is  about  520°  C.  (965°  F.)  and 
after  heating  for  600  hours  it  has  about  two-thirds  the  mag- 
netism of  pure  iron.  The  magnetism  is  almost  completely 
destroyed  by  heating  for  a  few  minutes  at  750°  C.  (Hadfield  and 
Hopkinson,  /.  /.  &•  S.  /.,  1914,  I).  It  is  largely  employed  for 
railway  crossings  or  rails  subject  to  heavy  wear,  and  is  par- 
ticularly valuable  for  safes,  as  it  cannot  be  softened  by  any  known 
treatment.  Recently  it  has  had  quite  extensive  use  for  light 
armor. 

Silicon  steels,  according  to  Guillet,  should  not  contain  more 
than  5%  of  silicon,  as  above  this  they  are  apt  to  be  brittle. 
While  the  cutting  capacity  of  a  tool  is  increased  to  a  certain 
extent,  this  is  obtained  without  the  other  advantages  result- 
ing from  the  use  of  other  elements.  With  about  1.5  to  2% 
silicon  and  low  carbon  and  manganese  a  grade  has  been  ob- 
tained especially  suitable  for  transformer  sheets  and  similar 
electrical  purposes  owing  to  the  low  magnetic  hysteresis  and 
high  permeability.  With  about  the  same  silicon  but  about  0.45 
to  0.65%  carbon  and  0.5  to  0.8%  manganese  (silico-manganese 
steel)  it  has  found  considerable  application  for  springs.  With 
less  than  0.5  %  silicon  it  is  not  generally  corfsidered  as  a  special 
steel. 

Vanadium  steels  may  be  roughly  divided  into  two  classes: 
those  used  for  general  purposes,  such  as  automobile  and  similar 
parts  (including  springs),  where  the  vanadium  content  varies 
from  about  o.i  to  0.25%;  and  special  tool  steel  where  the  con- 
tent will  commonly  be  about  0.5  to  i  %.  Vanadium  raises 
both  the  tensile  strength  and  the  elastic  limit,  the  latter  more 
than  the  former.  It  confers  the  valuable  property  of  making 
the  metal  very  resistant  to  repeated  stresses,  and  on  this  ac- 
count such  steel  is  sometimes  termed  anti-fatigue  steel.  Aside 
from  the  direct  benefit,  there  is  an  indirect  effect  due  to  the 
removal  of  oxygen  (either  as  oxide  or  gas),  and  probably  also 
of  the  nitrogen,  with  which  part  of  the  vanadium  combimes 
and  passes  off  into  the  slag. 


SPECIAL  TOOL  STEEL— SPECIFICATIONS         453 

Titanium  steels  (or  more  properly  titanium-treated  steels) 
are  those  to  which  a  small  amount  of  titanium  (usually  as  ferro- 
titanium)  has  been  added  just  before  pouring. 

The  following  steels  have  not  so  far  achieved  any  commercial 
prominence : 

Aluminum  steels,  according  to  Guillet,  when  containing 
less  than  3  %  of  aluminum,  do  not  differ  sensibly  in  their  proper- 
ties from  ordinary  steels;  above  this  percentage  the  elongation 
is  considerably  reduced  and  the  brittleness  increased. 

Boron  steels,  according  to  the  same  authority,  have  no  com- 
mercial application  in  the  natural  state,  but  might  prove  use- 
ful after  quenching.  In  that  condition  they  have  high  tensile 
strength  and  elasticity  and  are  no  more  brittle  than  other 
special  steels  at  present  in  use.  The  most  interesting  results 
were  obtained  with  a  steel  containing  0.5%  of  boron. 

Cobalt  steels,  containing  up  to  30%  of  cobalt,  have  been 
examined  by  Guillet.  The  only  item  of  commercial  interest 
he  noted  was  that  they  did  not  resemble  nickel  steels,  although, 
from  the  fact  that  nickel  and  cobalt  have  very  similar  proper- 
ties, this  would  have  been  expected. 

Copper  steels,  according  to  Breuil,  containing  above  4% 
of  copper,  are  incapable  of  being  rolled,  but  with  a  smaller 
percentage  the  strength  and  toughness  are  increased,  some- 
what as  with  nickel.  (See  also  Protection,  page  371.) 

Platinum  steels,  containing  small  percentages  of  platinum, 
have  been  stated  to  be  malleable  and  easily  worked,  but  very 
hard. 

Tin  steels,  with  up  to  about  10%  of  tin,  have  been  experi- 
mented upon  by  Guillet,  but  the  material  could  not  be  forged 
except  with  very  small  percentages;  in  certain  respects  they 
somewhat  resembled  silicon  steels. 

Uranium  steels  have  recently  been  manufactured  to  a  certain 
extent.  It  is  claimed  that  a  small  addition  (0.2  to  0.3  %)  largely 
replaced  tungsten  in  tool  steels,  but  definite  information  is  not 
available. 

Special  Tool  Steel.— See  page  445. 

Specific  Gravity.— See  Density. 

Specific  Heat— See  page  201. 

Specific  Heat  Pyrometer. — See  page  207. 

Specific  Line  of  Deformation. — See  page  126. 

Specific  Path  of  Deformation. — See  page  283. 

Specific  Tenacity.— See  page  336.  . 

Specific  Work  of  Rupture. — See  page  481. 

Specifications. — Specifications  for  the  purchase  of  iron  and  steel 
products  are  primarily  an  explanation  or  description — chemical, 
physical  and  mechanical — of  the  material  desired  for  a  given 
purpose  or  service,  and  provisions  for  tests  and  inspection  to 
afford  the  purchaser  reasonable  assurance  that  he  is  obtaining 
the  properties  stipulated.  Requirements  for  marking  for 
test  and  service  identification  and  permissible  variations  from 
ordered  dimensions  and  weights  are  generally  included,  and 
sometimes  definitions  of  terms  and  directions  for  packing  and 


454  SPECIFICATIONS 

shipping.  For  special  materials  certain  manufacturing  limita- 
tions may  be  specified,  e.g.,  a  minimum  amount  of  discard  from 
ingots,  a  maximum  amount  of  chipping  on  billets,  the  control  of 
rolling  temperatures,  and  directions  for  conducting  heat  treating 
operations. 

Although  the  commercial  manufacture  of  iron  and  steel  is 
based  on  scientific  principles,  the  results  secured  cannot  be 
predicted  with  mathematical  accuracy  owing  to  the  practical 
limitations  of  mill  operations.  It  is,  therefore,  essential  in 
writing  specifications  to  have  some  knowledge  of  manufacturing 
processes,  including  the  methods  and  possibilities  of  heat  treat- 
ment, and  a  wide  experience  in  testing  the  particular  material 
which  the  specifications  are  to  cover. 

Specifications  should  be  based  on  the  indications  offered  by  a 
sufficient  number  of  representative  cases;  experience  being  neces- 
sary to  avoid  employing  extremes,  simple  averages  or  figures  of 
an  unusual  or  irregular  nature.  Unfortunately  it  is  not  always 
possible  to  develop  tests  which  will  indicate  the  suitability  of  the 
material  for  a  given  service.  The  tests  specified  should  furnish 
definite  information  as  far  as  possible  and  those  of  an  indefinite 
or  irrelevant  character  should  be  disregarded  not  only  as  being 
of  no  value,  but  also  likely  to  interfere  with  the  production  or 
employment  of  suitable  material.  Requirements  should  not  be 
drawn  rigidly  simply  to  guard  against  incompetent  or  insufficient 
inspection,  and  it  is  unjust  to  make  the  requirements  for  material 
severe  on  the  plea  that  they  are  necessary  to  cover  irregularities 
in  material  and  service  conditions  and  to  provide  a  sufficient 
factor  of  safety — perhaps  more  accurately  "factor  of  ignorance" 
— but  more  probably  on  account  of  lack  of  the  necessary  engineer- 
ing data.  Proper  design  has  quite  as  much  and  often  more  to 
do  with  the  serviceability  of  an  object  than  the  quality  of  the 
material  from  which  it  is  made. 

In  the  United  States  there  are  a  number  of  technical  societies 
that  issue  specifications  for  iron  and  steel  products.  These 
include  the  Association  of  American  Steel  Manufacturers, 
American  Railway  Engineering  Association,  Master  Car  Builders 
Association,  American  Railway  Master  Mechanics  Association, 
American  Electric  Railway  Engineering  Association,  Society 
of  Automotive  Engineers,  and  American  Society  of  Mechanical 
Engineers,  but  the  Standards  of  the  American  Society  for 
Testing  Materials  are  fast  becoming  the  national  commercial 
specifications.  The  term  "commercial"  is  used  here  in  its 
broadest  sense  because  the  American  Society  for  Testing 
Materials  specifications  are  due  to  the  joint  work  of  the  con- 
suming and  the  producing  interests  to  which  is  added  the  inter- 
mediate experience  of  independent  or  consulting  engineers. 
As  a  result  of  an  extensive  system  of  committees,  recent  develop- 
ments will  always  be  found  in  the  specifications  contained  in 
the  Book  of  Standards  (triennial)  and  the  reports  of  committees 
in  the  Proceedings  (annual).  There  are  now  (1918)  41  specifica- 
tions for  steel,  5  for  wrought  iron,  and  6  for  cast  iron  products 
including  pig  iron. 


SPECIFICATIONS 


455 


In  referring  to  different  kinds  of  steels  for  various  purposes, 
the  following  distinctions  should  be  made:  Any  divisions  of 
products  by  size  or  designations  of  service  to  be  covered  by  the 
term  class ;  the  term  type  to  designate  kinds  of  steel,  that  is, 
whether  plain  carbon  or  the  various  divisions  of  alloy  steels; 
and  the  term  grade  to  designate  the  divisions  of  any  type  by 
carbon  content  or  physical  properties.  As  the  various  grades 
overlap  and  as  some  have  chemical  limits  only  while  others 
have  physical  limits,  a  table  or  chart  showing  chemical  and 
physical  requirements,  with  the  allowable  variations,  for  the 
different  classes  of  iron  and  steel  products,  would  be  intricate 
and  cumbersome.  Furthermore,  the  terms  low  carbon,  medium 
carbon,  and  high  carbon,  or  soft  (or  mild),  medium  and  hard 
must  be  considered  in  connection  with  the  context;  thus  a  hard 
structural  steel  of,  say,  0.35  carbon,  is  much  lower  in  this  element 
than  a  soft  spring  steel  with  0.70%.  The  safest  and  best 
method  to  follow  is  to  furnish  specific  details  and  not  trust  to 
indefinite  and  ambiguous  generalities. 

The  following  table  will  give  an  approximate  idea  of  the  ordi- 
nary designations  of  carbon  steels  now  in  use : 


Approximate 
Carbon  Range  Common  Uses 

o .  08-0 . 1 8  Pipe,  chain  and  other  welding  pur- 
poses; casehardening  purposes; 
rivets;  pressing  and  stamping 
purposes. 

o.  15-0.  25  Structural  plates,  shapes  and  bars 
for  bridges,  buildings,  cars,  loco- 
motives; boiler  (flange)  steel; 
drop  forgings;  bolts. 
Structural  purposes  (ships) ;  shaft- 
ing; automobile  parts;  drop  forg- 
ings. 

o .  35-0 . 60  Locomotive  and  similar  large  forg- 
ings; car  axles;  rails.. 

0.60-0.85  Wrought  steel  wheels  for  steam 
and  electric  railway  service;  loco- 
motive tires;  rails;  tools,  such  as 
sledges,  hammers,  pick  points, 
crowbars,  etc. 

o .  85-1 . 05  Automobile  and  other  vehicle 
springs;  tools,  such  as  hot  and 
cold  chisels,  rock  drills  and  shear 
blades. 

0.90-1.15  Railway  springs;  general  machine 
shop  tools. 

Since  about  1905  the  term  structural  steel  has  been  assigned 
to  a  definite  grade  of  about  0.15  to  0.25  carbon  or  55,000  to  70,000 
pounds  per  sq.  in.  in  tensile  strength.  Previously  the  following 
divisions  were  in  common  use: 


Grades 
Extra  soft 
(dead  soft) 


Structural  (soft 
medium) 


Medium 0.20-0.35 

Medium  hard. . 
Hard 

Spring... 

Spring 


456  SPECIMEN— SPITTING       . 

Tensile  Strength 
Grade  Carbon  Per  cent.  Pounds  per  square  inch 

Soft  Bessemer 0.08  to  o.  10 1        55,000  to  65,000 

Soft  Open  Hearth 0.15  to  o .  22  / 

Medium  Open  Hearth. .     o.  1 8  to  0.30          60,000  to  75,000 
Hard  Open  Hearth over  o .  30  over        70,000 

Specimens  for  Metallographic  Examination. — Preparation  of:  see 

page  ooo. 

Specimen  Tests.— See  page  467. 
Spectral  Pyrometer.— See  page  208. 
Spectroscope.— See  page  82. 
Spectrum  Analysis. — See  page  82. 
Specular  Iron  Ore. — See  page  243. 
Specular  Pig  Iron  (obs.). — See  page  355. 
Speed  of  Testing.— See  page  475. 
Speed  of  Transformation. — See  page  265. 
Spell. — (i)  To  work  intermittently  on  a  job  on  account  of  the 

severity  of  the  labor,  there  being  usually  two  gangs  or  shifts 

for  each  turn;  (2)  one  such  period  of  work. 
Spellerizing. — See  page  369. 
Spelter. — Crude  zinc  before  refining,  commonly  used  in  galvanizing. 

Hard  spelter  is  the  name  given  to  the  zinc  recovered  by  melting 

the  dross  removed  from  the  bottom  of  the  galvanizing  bath; 

it  contains  about  10%  of  iron. 
Spent  Acid.— See  Pickling. 
Spent  Bone. — See  page  68. 
Spent  Ore. — See  page  258. 
Sperry  Ore. — See  page  244. 
Sphaerosiderite. — See  page  244. 
Spheroidizing. — See  page  274. 
Spheroidizing  Graphite. — See  page  38. 
Spherolitic  (rare). — Round  in  shape  like  a  sphere. 
Spherule. — See  page  292. 

Spherulite;  Spherulitic  Structure. — See  page  125. 
Spicule. — See  page  123. 
Spiegel;  Spiegeleisen.— See  page  355. 
Spiegel  Recarburized. — Recarburized   with   spiegeleisen,   e.g.,   in 

the  case  of  Bessemer  rail  steel. 
Spielfield  Process. — See  page  380. 
Spike. — Of  structure;  see  page  128. 
Spike  Indicator. — See  page  210.  • 
Spill,  Spilly. — See  Pit. 
Spin  Up. — Of  crucibles;  see  page  112. 
Spindle. — See  page  403. 
Spindle  Temper.— See  Temper. 
Spiral  Pyrometer,  Fery. — See  page  207. 
Spiral  Seam. — See  Seam. 

Spirally  Riveted  Pipe;  Welded  Pipe.— See  page  489. 
Spirit  Thermometer. — See  page  205. 
Spitting. — The  ejection  of  small  particles  of  molten  metal  or  slag, 


SPLAYED— STABLE  EQUILIBRIUM  457 

usually  when  somewhat  thick  or  pasty,  by  gas  which  has  formed 

underneath. 
Splayed.— Of  the  shape  of  the  groove  in  a  swage,  etc.,  having  a 

greater  angle  or  curvature  than  the  finished  section  of  the  object 

for  which  it  is  used. 
Splendent  Fracture. — See  page  178. 
Splint  Coal.— See  Coal. 
Splintery  Fracture. — See  page  178. 
Split.— (i)  Generally  of  the  end  of  a  rolled  piece  when  the  end 

opens  up,  due  to  a  pipe  or  to  the  metal  being  red-short;  (2)   in 

casehardening:  see  page  68. 
Split  Weld. — See  page  502. 
Sponge. — Metal  in  a  porous  form,  generally  obtained  by  reduction 

without  fusion  (Raymond). 
Sponge  Bloom.— See  page  138. 
Sponge-like  Decay. — See  page  106. 
Sponge-making  Processes. — See  page  134. 
Sponginess;  Spongy.— See  page  55. 
Spontaneous  Absorption  of  Heat. — See  page  199. 
Spontaneous  Annealing. — See  page  334. 
Spontaneous  Combustion. — See  page  202. 
Spontaneous  Cracking. — See  pages  99  and  332. 
Spontaneous  Crystallization. — See  page  269. 
Spontaneous  Evolution  (Liberation). — Of  heat:  see  page  199. 
Spoon. — An  instrument  for  taking  samples  of  metal  while  molten, 

consisting  of  an  iron  cup  or  dish  attached  to  a  rod;  also  called 

sample  spoon  or  test  spoon. 
Sporadosiderite. — See  page  291. 
Spot  Chipping. — See  Chipping. 
Spot  Welding. — See  page  504. 
Spotted  Iron. — See  page  342. 
Spout.^— The  trough  which  conducts  the  molten  metal,  etc.,  from  a 

furnace;  in  a  blast  furnace  this  is  usually  called  the  runner. 
Spouting. — The  pipe  or  material  for  spouts. 
Spread. — In  rolling;  see  page  408. 
Spreader. — A   tool   for   spreading   refractory   material    (fettling) 

over  a  furnace  bottom. 
Spreader  Tuyere. — See  page  32. 

Spreading  and  Turning  (Eng.). — In  rolling:  see  page  414. 
Sprig;  Sprigging.— See  page  300. 
Spring  Heat. — See  page  71. 
Sprue. — (i)  Of  castings,  runner  scrap;  see  page  300:  (2)  a  projection 

left  on  a  casting  to  be  broken  off  and  used  for  testing  purposes 

(rare). 

Sprue  Heat. — See  page  257. 
Sprung. — See  page  56. . 
Spy. — See  page  70. 
Squeezer. — (i)  In  puddling:  see  page  377;  (2)   in  molding:  see 

page  301. 

Squeezer  Board. — See  page  301. 
Stable  Diagram. — See  page  271. 
Stable  Equilibrium. — See  page  326. 


458  STACK— STEAM  HAMMER 

Stack. — (i)  A  blast  furnace;  (2)  a  large  high  chimney. 

Staff. — See  page  79. 

Stage. — In  comparison  with  phase:  see  page  326. 

Stainless  Steel. — See  pages  367  and  451. 

Stall. — Seepage  181. 

Stamps. — See  page  79. 

Stamping. — See  Marking. 

Stampings. — See  page  378. 

Stand -By  (Eng.). — A  spare,  as  an  extra  part  for  replacement. 

Stand. — Of  rolls:  see  page  406. 

Standards. — Of  a  rolling  mill;  see  page  403. 

Standard  Bessemer  Pig. — See  page  344. 

Standard  Coil.— See  Coil. 

Standard  Ferro -Manganese. — See  page  352. 

Standard  Foundry  and  Furnace  Coke. — See  page  96. 

Standard  Roasted  Dolomite. — See  page  399. 

Standard  Solution. — See  page  83. 

Standard  Test  Piece.— See  page  473. 

Standard  Wire  Gage.— See  page  188. 

Standardization. — Of  a  testing  machine:  see  page  469. 

Stanton  Test— (i)   Impact  test:  see  page  482;  (2)  wear  test:   see 

page  480. 

Star  Fracture. — See  page  178. 
Star-like  Crystallite. — See  page  122. 
Stare. — Of  a  fracture:  see  page  115. 
Stassano  Furnace. — See  page  163. 
State,  Changes  of. — See  page  81. 
State  Diagram. — See  page  271. 
State  of  Ease. — See  page  332. 
Static  Hardness. — See  page  331. 

Static  Indentation. — To  determine  hardness:  see  page  477. 
Static  Load. — See  page  333. 
Static  Metamorphism. — See  page  122. 
Static  Strength. — See  page  330. 
Static  Stresses. — See  page  333. 
Static  Test.— See  page  468. 
Stationary  Bottom. — See  page  182. 
Stationary  Converter. — See  page  17. 
Stationary  Furnace. — See  page  312. 
Stationary  Table.— See  page  408. 
Stationary  Top. — Of  a  blast  furnace:  see  page  32. 
Stave. — (i)  Pieces  of  wrought  iron  welded  together  as  a  basis  for 

making  shafts,  etc.;  (2)  to  swell  up  the  end  of  a  tube. 
Stay  Tubes. — In  a  boiler,  a  few  of  the  tubes  which  are  heavier  than 

the  rest  and  have  a  nut  screwed  on  the  ends  outside  the  boiler 

shell  to  keep  it  from  bulging  outward. 
Stead's  Brittleness. — See  page  216. 
Stead's  Law. — Of  welding:  see  page  501. 
Stead's  Reagents. — See  page  287. 
Stead  Test.— See  page  482. 
Steadite. — See  page  277. 
Steam  Hammer. — See  Hammer. 


STEAM  HELVE— STERLING'S  CAST  IRON         459 

Steam  Helve. — See  Hammer. 

Steam  Refinery. — See  page  383. 

Steam  Shears. — See  page  412. 

Steaming. — See  Water  Gas. 

Steel. — (i)  That  form  of  iron  produced  in  a  fluid  condition,  and 
hence  practically  free  from  slag  (difference  from  wrought  iron), 
which  contains  less  than  about  2.20%  of  carbon — as  a  rule 
less  than  1.50%  (difference  from  cast  iron).  It  is  produced 
by  the  crucible,  the  Bessemer,  and  the  open  hearth  process, 
and  also  in  the  electric  furnace.  (2)  The  product  obtained  by 
carburizing  wrought  iron  (more  rarely  low  carbon  steel)  by 
the  cementation  process,  and  generally  known  as  cement  steel. 
(3)  Formerly  steel  was  what  could  be  hardened  ( usefully )  by 
quenching,  while  iron  could  not. 

Steel  Bronze. — An  alloy  of  about  90  %  copper  and  10  %  tin  (bronze) 
which  on  account  of  its  strength  and  hardness  is  sometimes  used 
in  place  of  steel,  particularly  to  resist  corrosion. 

Steel-cast  (adj.)- — Suggested  to  be  used  to  indicate  that  a  given 
object  was  a  steel  casting,  as  it  was  claimed  that  it  would  obviate 
any  question  as  to  whether  crucible  steel  was  meant,  as  would 
be  the  case  if  "cast  steel"  were  used  indiscriminately.  Crucible 
steel  should  always  be  called  "crucible  steel,"  and  the  above 
term  dropped. 

Steel  Castings. — Castings  made  of  steel  and  not  subsequently  forged 
or  rolled. 

Steel  Cleaning  Sand. — See  page  296. 

Steel-faced  Wrought  Iron  Armor  Plate. — See  page  8. 

Steel  Facing. — See  page  166. 

Steel  Iron  (Eng.). — Pig  iron  intended  for  conversion  into  steel. 

Steel  Ladle.— See  Ladle. 

Steel  Melting-heat  Processes. — See  page  134. 

Steel  Mold. — See  page  296. 

Steel  Molding  Sand;  Steel  Sand.— See  page  296. 

Steel  Side.— See  page  18. 

Steel -through  Heat. — ^See  page  71. 

Steel  Wire  Gage.— See  page  186. 

Steel  Wool. — An  abrasive  material  consisting  of  very  fine  shavings 
of  steel  wire  made  by  a  special  machine. 

Steely  Malleable. — White  heart  malleable;  see  page  258. 

Stefan-Boltzmann's  Law. — Of  radiation:  see  page  207. 

Stefan's  Law. — Of  radiation:  see  page  207. 

Stellar  Pyrometer. — See  page  208. 

Stellate  Structure.— See  page  125. 

Stellate  Twin.— See  page  124. 

Step. — See  page  282. 

Stereo-Chemistry. — See  page  86. 

Stereo-Formula. — See  page  86. 

Stereoisomer. — See  page  86. 

Stereoscopic  Binocular  Microscope. — See  page  285. 

Stereoscopic  Radiograph. — See  page  285. 

Sterling  Process.— See  page  118. 

Sterling's  Toughened  Cast  Iron.— See  Semi-Steel. 


460  STEWING— STRAIGHTENING  ROLL 

Stewing. — See  page  376. 

Sticker. — (i)  An  ingot  from  which  it  is  difficult  to  remove  the  mold 

on  account  of  sticking;  (2)  a  pack  in  which  the  sheets  stick 

together:  see  page  430. 
Sticking. — (i)  Of  the  charge  in  a  blast  furnace,  hanging;  see  page 

35;  ^2)  of  an  ingot  which  is  not  easily  removed  from  the  mold; 
(3)  in  welding:  see  page  504. 
Stiefel  Process. — See  page  491. 
Stiff ener. — See  page  406. 
Stiffness. — See  page  330. 
Stinking  Coal.— See  Coal. 
Stirring  Rod. — A  rod  or  bar  of  iron  or  soft  steel  used  in  working  an 

open  hearth  heat. 
Stock. — (i)   What  is  on  hand  ready  for  delivery;   (2)   the  raw 

material  used  for  charging  a  furnace  in  the  manufacture  of  iron 

and  steel;  (3)  the  foundation  for  the  anvil  of  a  power  hammer. 
Stock  Coke. — See  page  97. 
Stock  Converter  Process. — See  page  22. 
Stock  House. — A  building   or   structure   to   keep   under   shelter 

materials  used  in  manufacturing. 

Stock  Indicator;  Line. — Of  a  blast  furnace:  see  page  35. 
Stock  Pile. — The  pile  of  ore  constituting  the  supply  for  a  blast 

furnace,  particularly  during  the  winter  months. 
Stockman  Process. — See  page  388. 
Stone. — (i)  Limestone;  (2)  in  connection  with  wire:  see  page  95; 

(3)  a  meteorite:  see  page  291. 
Stool.— See  page  57. 
Stopper.— See  Ladle. 
Stopper;  Stopper  Down  (Eng.). — To  close  or  stop  up  a  hole,  e.g., 

the  tapping  hole  of  a  furnace,  or  the  hole  in  the  top  of  an  ingot 

mold;  to  cap. 

Stopper  Head.— See  Ladle. 
Stoppering  (Eng.). — Closing  up. 
Stopping. — Material  used  for  closing  up  a  hole. 
Stopping  In. — See  page  182. 
Stoughton  Converter. — See  page  24. 
Stove. — See  pages  27  and  34. 
Stove  Coke. — See  page  97. 
Straight  Open  Hearth  Processes. — See  page  310. 
Straight  Pane.— See  Pane. 

Straightening  Mangle  (Eng.). — Straightening  rolls,  q.v. 
Straightening  Press. — Or  gag  press;  a  machine  consisting  of  a 

fixed  straight  side  and  a  movable  side,  operated  by  a  cam  or 

eccentric,  which  is  brought  against  a  bar  resting  against  the 

piece  where  it  is  bent,  to  straighten  it. 
Straightening  Rolls. — A   machine   comprising   an   upper   and   a 

lower  set  of  several  rolls  each,  the  rolls  in  the  two  sets  being 

staggered.     The  distance  between  the  two  sets  is  so  regulated 

for  pieces  of  different  gage  that  in  passing  through  they  are 

made   perfectly   flat,   i.e.,   straight.     For   plates   the   rolls   are 

plain,    while   for   shapes    they   contain   grooves    corresponding 

to  the  section.     See  also  page  414. 


STRAIN— STUBS'  GAGE  .  461 

Strain. — (i)  General:  see  page  333;  (2)  effect  on  growth  of  ferrite: 
see  page  216;  (3)  effect  on  grain  growth:  see  page  216;  (4)  effect 
of  time  beyond  elastic  limit:  see  page  472. 

Strain  Gage. — See  page  471. 

Strain  Hardness. — See  pages  99  and  331. 

Strand  Rolls. — See  page  414. 

Stranded  Wire. — See  page  509. 

Stratification. — A  formation  consisting  of  layers  or  bands. 

Stratification  Foliation. — See  page  1 24. 

Straw  Temper. — Oxide  color:  see  page  230. 

Straw  Tinted  Wire. — See  page  508. 

Streaks. — See  Seam. 

Stremmatograph. — See  page  484. 

Strength. — See  page  330. 

Strength  of  Materials. — See  page  330. 

Stress. — (i)  General:  see  page  331;  (2)  lines  of:  see  page  283. 

Stress -Deformation  Diagram. — See  page  471. 

Stress  Difference. — See  page  333. 

Stress-Strain  Diagram. — See  page  471. 

Stress  Theories. — Of  hardening:  see  pages  279  and  280. 

Stretch. — See  page  336. 

Stretch  Limit. — See  page  471. 

Strickle. — See  page  301. 

Striction. — See  page  336. 

Stridberg's  Hearth. — See  page  79. 

Stridsberg  Process. — See  page  62. 

Striking;  Striking  Up. — See  page  301. 

Striking  Energy. — See  page  481. 

Stringing  Up.— Of  wire:  see  page  508. 

Strip. — (i)  Of  ingots,  to  remove  the  mold;  (2)  of  patterns,  the  taper 
or  draft:  see  page  296;  (3)  a  coil:  see  page  95;  (4)  of  mines 
which  are  open  worked,  to  remove  the  surface  covering. 

Strip  Mill. — See  page  415. 

Stripper;  Stripping.— See  page  57. 

Stripping  Plate. — (i)In  molding :  see  page  300;  (2)  in  a  rolling  mill: 
see  page  41 5. 

Stroh  Steel  Hardening  Process. — See  page  504. 

Stromborg  Process.— See  page  147. 

Strong  Contact  Metal  Theories.— See  page  282. 

Strong  Iron. — Close-grained,  gray  pig  iron. 

Structural  Composition. — See  page  337. 

Structural  Formula. — (i)  In  chemistry:  see  page  86;  (2)  for  phys- 
ical properties:  see  pages  337  and  339. 

Structural  Properties. — Formulae  for:  see  page  337. 

Structural  Saturation  Point.— See  page  273. 

Structural  Steel. — Classification:  see  page  455. 

Structural  Tests.— See  page  468. 

Structurally  Free  Cementite. — See  page  273. 

Structurally  Free  Ferrite. — See  pages  272  and  275. 

Structure. — See  pages  125  and  289. 

Structure  of  Crystals. — See  page  121. 

Strut.— See  page  468. 

Stubs'  Gage. — For  iron  wire  and  steel  wire:  see  page  188. 


462  STUCK  OVEN— SULPHUR 

Stuck  Oven. — See  page  147. 

Stiickofen. — See  page  147. 

Stud. — See  page  299. 

Stud  Gage. — See  page  186. 

Styloid. — See  page  290. 

Styrian  Charcoal  Process;  Open  Hearth;  Raw  Steel  Process.— 
See  page  79. 

Styrian  Walloon  Process. — See  page  80. 

Subaerial  (rare). — In  air,  e.g.,  rusting;  in  contradistinction  to 
subaqueous. 

Subaqueous. — In  water. 

Subcarbide  Theory. — Of  hardening:  see  page  280. 

Subcarburized  (obs.). — Applied  to  steel,  meaning  very  low  in 
carbon  like  wrought  iron. 

Subcooling. — In  hardening:  see  page  279. 

Subcrystalline. — Non-crystalline  and  in  unstable  equilibrium. 

Subcutaneous  Blowhole. — See  page  55. 

Sublimation. — See  page  202. 

Sub-punching. — See  Cold  Working. 

Sub -transformation  Range. — See  page  271. 

Suction  Producer. — See  Producer. 

Sudden  Cement. — See  page  67. 

Sudden  Fracture. — See  page  178. 

Sudden  Load. — See  page  333. 

Sudre  Process. — See  page  118. 

Sull. — Coating:  see  page  507. 

Sullage. — See  page  56. 

Sullage  Piece. — See  page  56. 

Sulphide  Area. — See  page  289. 

Sulphide  Coating. — See  page  374. 

Sulphide  Ore. — See  page  245. 

Sulpho-Film. — See  page  289. 

Sulphur.— S;  at.  wt.,  32;  melt,  pt,  114.5°  C.  (238°  F.);  boil,  pt., 
448°  C.  (838°  F.);  sp.  gr.,  rhombic,  2.05,  prismatic,  1.98, plastic, 
1.95.  It  is  found  both  free  and  combined.  When  pure  and 
in  its  ordinary  condition  it  is  a  pale  yellow,  crystalline  solid. 
It  may  exist  in  four  allo tropic  varieties:  (i)  rhombic  crystals, 
stable  at  ordinary  temperatures;  (2)  prismatic  needles,  ob- 
tained by  allowing  melted  sulphur  to  cool  slowly;  unstable 
at  ordinary  temperatures,  and  tending  to  pass  back  to  the 
rhombic  variety;  (3)  plastic  sulphur  (amorphous),  obtained 
by  heating  sulphur  until  it  reaches  a  certain  viscous  condition, 
and  then  pouring  it  into  water;  unstable  at  ordinary  tem- 
peratures; (4)  white  amorphus  sulphur,  obtained  by  sublima- 
tion; stable  at  ordinary  temperatures.  Sulphur  combines 
with  iron  to  form  ferrous  sulphide,  FeS,  and  ferric  sulphide 
FeS2  (pyrites).  With  manganese  it  forms  mangansee  (man- 
ganous)  sulphide,  MnS,  which  is  nearly  if  not  quite  insoluble 
in  metallic  iron.  In  ordinary  steel  it  usually  runs  from  about 
0.02  to  0.10%.  If  combined  with  iron  its  effect  is  to  make 
the  metal  red-short,  and  it  sometimes  appears  to  exert  a  slight 
similar  effect  on  the  metal  when  cold.  In  cast  iron  it  makes 


SULPHUR  ADDITIONS— SURPLUS  CARBIDE      463 

the  molten  metal  thick  and  sluggish,  and  appears  to  reduce  the 
saturation  point  for  carbon,  and  to  keep  that  present  in  the 
combined  state.  What  is  termed  a  sulphur  ball  is  a  segregate 
very  high  in  sulphur  which  sometimes  separates  out  from  high 
sulphur  pig  during  solidification.  For  influence  on  corrosion 
see  page  366. 

Sulphur  Additions. — See  Recarburization. 

Sulphur  Ball.— See  Sulphur. 

Sulphur  Coal.— See  Coal. 

Sulphur  Print.— See  page  288. 

Sulphuric. — Sulphur  in  chemical  combination  in:  its  highest  valence 
VI. 

Sulphurous. — (i)  Containing  a  large  or  excessive  percentage  of 
sulphur;  (2)  sulphur  in  chemical  combination  in  its  lower  valences 
II  or  IV. 

Summerlee  Process. — Same  as  the  Neilson  process,  for  the  recovery 
of  tar  and  ammonia  from  the  gas  of  a  blast  furnace  using  raw 
coal. 

Supercarburized. — Cemented;  used  for  Harvey  process:  see  page 
67. 

Superficial  Cementation. — See  page  67. 

Superfusion. — See  page  268. 

Superheated. — (i)  Of  steel:  see  page  202;  (2)  of  blast,  heated  in 
modern  fire-brick-stoves  to  above  600°  F.  (315°  C.),  which  was 
about  the  limit  of  temperature  with  the  old  cast-iron  pipe  stoves ; 
(3)  of  steam  which  has  been  heated  to  above  the  temperature  at 
which  moisture  can  form,  and  out  of  contact  with  water;  dry 
steam. 

Supermolten. — See  page  202. 

Superpxidation. — Oxidation  beyond  what  is  usual,  as  for  special 
purification  in  the  electric  furnace  process,  etc. 

Superposing  Method. — See  Alloy. 

Supersaturated  Solution. — See  Solution. 

Supersaturated  Steel. — See  page  273. 

Supersilicated  (rare). — Containing  a  large  (or  extra)  percentage  of 
silica,  e.g.,  of  slag. 

Supersolubility  Curve. — See  page  269. 

Surface  Band. — See  page  127. 

Surface  Blowhole. — See  page  55. 

Surface  Cementation. — Case  hardening:  see  page  67. 

Surface  Combustion. — See  page  203. 

Surface  Deformation. — See  page  283. 

Surface  Force. — See  page  331. 

Surface  Hardening. — Case  hardening:  see  page  67. 

Surface  Resistance. — See  page  200. 

Surface  Resistance  Furnace. — See  page  153. 

Surface  Scratching. — See  page  478. 

Surface  Traction. — See  page  331. 

Surfusion. — The  abnormal  or  unstable  condition  of  a  body  which, 
under  certain  conditions,  may  remain  liquid  after  the  tempera- 
ture has  fallen  below  the  freezing  point:  see  pages  268  and  327. 

Surplus  Carbide. — Cementite:  see  page  273. 


464          SURPLUS  FERRITE— SZEKELY  PROCESS 

Surplus  Ferrite. — See  page  272. 

Surzycki  Process. — See  page  317. 

Swab;  Swab  Pot— See  page  298. 

Swab  Up. — In  the  crucible  process:  see  page  115. 

Swaff  (Eng.).— Swarf. 

Swage  Work. — See  Hammer. 

Swan  Process. — See  page  367. 

Swarf  (rare). — Fine  particles  of  metal  (usually  iron  or  steel) 
produced  in  machining  or  grinding. 

Swarfing  Furnace. — See  page  379. 

Sweating. — A  method  of  fastening  two  metallic  surfaces  together  by 
means  of  a  very  thin  invisible  layer  of  solder. 

Sweating  Heat. — Wash  heat,  q.v. 

Swedish  Bessemer  Process. — See  page  23. 

Swedish  Fixed  Converter. — See  page  23. 

Swedish  Lancashire  Process. — See  page  77. 

Swedish  Metallic  Sponge.— See  page  147. 

Swedish  Walloon  Process. — See  page  79.. 

Sweep. — (i)  In  structural  shapes  and  rails,  side  curvature:  see 
page  49;  (2)  in  molding:  see  page  300. 

Sweep  Molding. — See  page  300. 

Sweeping  Up. — See  page  301. 

Swell.— (i)  A  defect  in  castings:  see  page  58;  (2)  in  cold  rolling  or 
drawing:  see  Cold  Working;  (3)  a  raised  portion  on  a  piece  of 
rolled  material,  such  as  a  rail,  from  the  pressure  of  gas,  in  a  gas 
pocket  located  near  the  surface,  while  the  metal  is  hot  and  soft. 

Swill. — In  pickling:  see  pages  341  and  431. 

Swording  Stickers. — See  page  430. 

Symbol. — In  chemistry:  see  page  86. 

Symmetry,  Law  of. — For  crystals:  see  page  120. 

Syndolag.— See  page  397. 

Synthesis;  Synthetic  Chemistry. — See  page  82. 

Synthetic  Reaction. — See  page  87. 

Synthetic  Steel. — The  opposite  of  natural  steel;  sometimes  applied 
as  in  the  case  of  an  alloy  steel  to  which  the  alloy  elements  are 
specially  added  in  amounts  as  desired,  as  opposed  to  natural  steel 
where  the  composition  depends  entirely  or  principally  on  the 
composition  of  the  ore. 

Syssiderite.— See  page  291. 

System. — (i)  In  connection  with  the  phase  rule:  see  page  326; 
(2)  of  crystallization:  see  page  120. 

Systemmatic  Deviation. — Of  slipping:  see  page  283. 

Szekely  Process.— See  page  65. 


T;  t. — T:  absolute  temperature;  transverse  (of  tests,  etc.);  t:  time; 

thickness. 

Ta. — Chemical  symbol  for  tantalum:  see  page  84. 
Tb. — Chemical  symbol  for  terbium:  see  page  84. 
Te. — Chemical  symbol  for  tellurium:  see  page  84." 
Th. — Chemical  sybmol  for  thorium:  see  page  84. 
Ti. — Chemical  symbol  for  titanium,  q.v. 
Tl. — Chemical  symbol  for  thallium:  see  page  84. 
Tm. — Chemical  symbol  for  thulium :  see  page  84. 
T.  A.  I.  M.  E. — Transactions  of  the  American  Institute  of  Mining 

Engineers. 

T  Hammer. — See  Hammer. 
T.U.— Thermal  or  heat  unit. 
Table. — See  page  407. 
Taenite  (Reichenbach). — See  page  291. 
Tag  Butt  Welding.— See  page  489. 
Tagger.— See  page  433. 
Tail  Helve.— See  Hammer. 
Take  the  Blast.— See  page  35. 

Take  a  Heat. — Melting  iron  in  a  cupola  for  foundry  work. 
Take  Off.— The  blast:  see  page  37. 
Talbot  Furnace. — See  page  316. 
Talbot  Process. — (i)  For  treating  ingots:  see  page  64;   (2)  open 

hearth  process:  see  page  316;  (3)  purification  process:  see  page 

384- 

Talbot  and  Stirling  Process. — See  page  118. 

Tamping. — (i)  A  molder's  term  which  signifies  the  ramming  up  of 
the  sand  around  a  pattern;  (2)  stopping  the  tap  hole  of  a  cupola 
furnace  with  clay;  the  term  is  derived  from  the  beating  down  a 
charge  into  a  hole  in  blasting  and  mining  operations  (Homer). 

Tandem  Continuous  Mill. — See  page  409. 

Tandem  Roughing  Mill. — See  page  416. 

Tangential  Stress. — See  page  332. 

Tank  Converter. — See  page  20. 

Tank  Cupola.— See  page  182.  0 

Tap. — Of  a  furnace:  see  page  315. 

Tap  Bar. — See  page  70. 

Tap  Cinder.— See  Slag. 

Tap  Hole.— See  page  311. 

Tap  Wagon  (obs.) .— A  ladle  of  small  size. 

Taper. — Of  a  foundry  pattern;  draft:  see  page  296. 

Tappet. — See  page  411. 

Tappings. — (i)  In  puddling:  see  page  377;  (2)  molten  metal  from 
the  blast  furnace  (obs.);  (3)  of  slag:  see  page  438. 
30  465 


466  TAPPING  HOLE— TEMPERATURE 

Tapping  Hole. — See  pages  32  and  182. 

Tapping  Rod. — A  rod  or  bar  used  to  open  the  tapping  hole  of  a 

furnace- 
Tapping  Slag.— See  Slag. 

Tardy  Hydrate. — Of  calcium  chloride:  see  page  30. 

Tarmac.— See  Slag. 

Taussig  Furnace. — See  page  164. 

Taylor  Process.— See  page  380. 

Taylor-White  Process;  Steel.— See  page  446. 

Teaming  (obs.). — Teeming:  see  page  57. 

Tear. — (i)  Of  metal  which  does  not  cut  crisply,  usually  the  fault 
of  the  tool;  (2)  the  rupture  of  material  in  drawing,  due  to  too 
heavy  draft  or  to  dirt  or  scale  in  the  die. 

Tearing  Stress. — See  page  336. 

Technical  Chemistry. — See  page  81. 

Tectotherm. — See  page  267. 

Tedge. — See  page  299. 

Teem;  Teeming.— See  pages  57  and  115. 

Teeming  Hole. — See  page  115. 

Telegraph. — A  hook  or  pair  of  tongs  suspended  by  a  rod  from  a 
pulley  running  on  an  overhead  beam  or  rail,  and  used  for  trans- 
porting small  billets,  puddle  balls,  etc. 

Temper. — (i)  Of  crucibles:  see  page  112;  (2)  hardness,  q.v. 

Temper. — The  percentage  of  carbon  in  steel  (usually  crucible 
steel)  with  special  reference  to  the  purpose  for  which  it  is  suitable: 
Razor  temper,  i>£%;  saw -file  temper,  i%%;  tool  temper  (drill 
temper),  ij^%;  spindle  temper,  i  J£%;  chisel  temper,  i%;  set 
temper,  %  %;  die  temper,  %  %.  Brearly  ("  Heat  Treatement  of 
Tool  Steel,"  page  10)  gives  the  following  figures: 

Die  Temper  0.70-0.75  approx.  carbon 

Smiths'  Tool  Temper  o .  80-0 . 85 

Shear  Blade  Temper  o .  90 

General  Purposes  Temper  o .  90-0 . 95 

Axe  Temper  o .  95-1 . 05 

Cutlery  Temper  i .  oo-i .  10 

Tool  Temper  i .  20-1 . 30 

Razor  Temper  i .  30-1 . 40 

The  content  of  carbon  also  may  be  roughly  indicated  by  the 
terms  low  temper  steel,  medium  temper  steel,  and  high  temper 
steel.  Irish  temper  was  a  grade  of  cement  bars  formerly  made 
containing  about  0.3  %. 

Temper  Carbon.— See  pages  257  and  278. 

Temper  Casting. — See  page  257. 

Temper  Graphite. — See  page  257. 

Temper  Test. — See  page  476. 

Temper  Tinting.— See  page  288. 

Temperability. — See  page  227. 

Temperature. — See  page  199. 

Temperature  Colors. — See  page  210. 

Temperature  of  Combustion. — See  page  203. 

Temperature-Density  Curve.— See  page  225. 


TEMPERATURE  INTERVAL— TESTING  467 

Temperature  Interval. — See  page  265. 

Temperature  Measurement. — See  page  204. 

Temperature  Stresses. — See  page  333. 

Tempered  Casting. — See  page  257. 

Tempering. — (i)  Of  steel:  see  pages  212  and  230;  (2)  of  molding 
sand:  see  page  296. 

Tempering  Charge. — See  page  233. 

Tempering  Colors. — See  page  230. 

Tempering  Martensite. — See  page  276. 

Tempering  Plate. — See  page  231. 

Tempering  Temperature. — See  page  230. 

Tenacity. — See  page  330. 

Tender.— Brittle,  q.v. 

Tensile  Formulae;  Properties.— See  page  337. 

Tensile  Resilience. — See  page  331. 

Tensile  Strain;  Strength;  Stress.— See  pages  330  and  333. 

Tensile  Test. — See  page  469. 

Tension;  Tensional. — Tensile. 

Terminal  Grain  Boundary. — See  page  283. 

Ternary  Alloy.— See  Alloy. 

Ternary  Compound. — See  page  88. 

Ternary  Steels.— See  page  443. 

Terne  Plate. — See  pages  371  and  432. 

Terre-Noire  Process. — (i)  For  quenching:  see  page  229;  (2)  for 
tempering:  see  page  233. 

Terreault  and  Hilzinger  Process. — See  page  258. 

Terrestrial  Iron. — See  page  291. 

Tertiary  Crystals. — See  page  121. 

Tesseral  System. — Of  crystallization:  see  page  120. 

Tessular  System. — Of  crystallization:  see  page  120. 

Test.— See  Furnace  Test. 

Test  Bar. — See  page  70. 

Test  to  Destruction. — See  page  467. 

Test  Piece. — Influence  of  form:  see  page  473. 

Test  Spoon. — See  Spoon. 

Testing. — (i)  In  general,  any  method  for  determining  the  chemical 
or  physical  quality  of  material;  (2)  specifically  (and  as  commonly 
understood),  the  determination  by  physical  means  (physical 
testing)  of  the  suitability  of  a  material  for  the  purpose  intended, 
and  having  no  direct  connection  with  the  chemical  composition 
or  defects  which  properly  belong  under  chemical  analysis  and 
inspection  respectively;  (3)  in  connection  with  ordnance  material, 
the  term  proving  (e.g.,  proving  ground)  is  employed,  and  for 
armor  plate  ballistically  tested,  the  term  attacking. 

Tests  may  be  divided  into  two  classes:  (a)  destructive  tests 
(testing  to  destruction),  where  it  is  desired  to  learn  the  ultimate 
properties;  and  (b)  proof  tests,  where  it  is  desired  to  impose  on 
material  or  objects,  actually  going  into  service,  tests  to  determine 
•  that  they  are  entirely  suitable.  Tests  are  commonly  made  on 
portions  or  samples  selected  to  represent  a  given  lot  (specimen 
tests),  usually  tested  to  destruction,  based  on  the  well  recog- 
nized assumption  that  material,  or  objects  of  such  material,  made 


468  TESTING  • 

and  treated  at  one  time,  is  commercially  uniform;  they  may 
also  be  made  on  entire  objects  (full-size  tests),  which  may  also 
be  specimen  tests.  When  made  on  built-up  objects  they  are 
sometimes  referred  to  as  structural  tests.  Tests  may  be  further 
divided,  depending  upon  the  nature  of  the  stresses  imposed, 
into  (c)  static  tests  or  slow  tests,  and  (d)  dynamic  tests  or 
impact  tests. 

Composite  structures,  such  as  bridges,  which  are  made  up  of 
many  component  parts  of  different  sizes  and  properties,  must 
be  designed  to  support  two  kinds  of  loads:  (a)  dead  loads,  or 
the  weight  of  the  structure  itself,  including  any  permanent 
fixtures,  and  (6)  live  loads  or  moving  loads,  such  as  people  or 
vehicles  passing  over  it.  A  uniform  load  is  one  which  is  evenly 
distributed  throughout  the  structure.  A  concentrated  load 
is  where  one  portion  is  more  severely  stressed  than  another, 
hence  moving  loads  may  also  be  referred  to  as  moving  concen- 
trated loads.  The  load  which  the  structure  is  designed  to  bear 
is  called  the  working  load,  and  the  corresponding  strength  re- 
quired, the  working  strength.  This  must  always  be  less  than 
the  elastic  resistance,  and  may  be  referred  to  as  the  permissible 
working  stress,  safe  range  of  stress  or  safe  load.  As  opposed 
to  this,  the  ultimate  strength  is  sometimes  called  the  absolute 
strength.  The  factor  obtained  by  dividing  the  ultimate  strength 
by  the  total  load  is  known  as  the  factor  of  safety;  French  engi- 
neers, as  a  rule,  base  this  factor  on  the  elastic  limit,  which 
may  be  considered  roughly  as  about  one-half  the  ultimate 
strength,  at  least  in  the  case  of  ordinary  structural  material. 
The  proof  load  or  proof  weight  is  the  load  applied  to  determine 
the  value  of  the  material  tested  when  it  is  not  intended  that 
observable  deformation  (or  above  a  prescribed  maximum 
value)  shall  take  place  (Thurston);  the  strength  required  for 
this  is  known  as  the  proof  strength,  and  is  usually  equal,  or  nearly 
so,  to  the  maximum  elastic  resistance  of  the  piece.  The  proof 
strain  (practical  proof  strain)  is  determined  by  taking  one-half 
of  the  intensity  of  the  stress  the  piece  can  sustain,  a  certain 
maximum  number  of  times,  without  injury. 

By  bar  is  understood  a  "piece  of  uniform  cross  section.  Its 
cross  sectional  area,  used  in  computing  certain  values,  is  fre- 
quently referred  to  as  cross  section,  section  area,  or  simply 
section.  A  bar  whose  length  is  over  about  eight  times  its  dia- 
meter or  thickness  is  called  a  column  or  strut  when  subjected 
principally  to  longitudinal  forces.  If  the  forces  act  principally 
transversely,  it  is  a  beam,  when  it  is  supported  near  the  ends,  a 
simple  beam;  when  it  is  supported  at  one  end  and  near  the  middle, 
the  other  end  being  unsupported,  a  cantilever  beam;  and  when 
supported  at  more  than  two  points,  a  continuous  beam. 

While  in  some  cases  the  specimen  tests  may  be  made  on  a 
finished  object  or  section,  such  as  a  railroad  axle  or  a  piece  of 
rail,  yet  ordinarily,  as  with  plates  and  shapes,  this  cannot  be 
readily  done,  and  hence  a  relatively  small  sample  or  test  piece 
is  taken.  Further  as  most  testing  is  carried  to  destruction  this 
prevents  a  large  amount  of  good  material  from  being  wasted 


TESTING  469 

unnecessarily.  If  the  length  of  the  test  piece  is  parallel  to  the 
direction  of  rolling  or  the  extension  which  the  material  has 
undergone,  it  is  called  a  longitudinal  test  piece;  if  perpendicular, 
a  transverse  test  piece. 

Tensile  Tests. — Also  called  tension  tests,  pulling  tests,  or, 
rarely,  traction  tests.  These  are  by  far  the  most  common  and 
are  carried  out  by  making  the  specimen  fast  at  one  end  and 
applying  a  load  (in  the  direction  of  its  length)  to  the  other  end 
until  it  has  been  pulled  apart.  For  material  of  very  small 
cross  section,  such  as  wire,  this  is  readily  done  by  suspending 
weights  to  it  (hanging  test),  but  with  larger  sections  requiring  a 
great  many  thousand  pounds  to  effect  rupture,  mechanical 
means  must  be  employed.  A  testing  machine  consists  essen- 
tially of  clamps,  grips,  or  shackles  for  holding  the  specimen; 
mechanism  for  applying  the  load  to  the  specimen;  a  lever  (beam) 
or  other  device  for  weighing  or  measuring  the  load;  and  a  heavy 
frame  for  holding  the  various  parts  together.  The  machine  is 
vertical  or  horizontal,  depending  upon  the  respective  position 
in  which  the  specimen  is  held.  The  power  is  usually  furnished 
by  an  electric  motor  (the  variable  speed  type  is  coming  largely 
into  use)  or  in  some  cases,  particularly  for  very  large  machines 
of  a  million  or  more  pounds  capacity,  it  may  be  hydraulic.  With 
the  common  type  of  machines  it  is  measured  in  the  same  manner 
as  with  an  ordinary  scales  by  a  jockey  weight  or  rider  which  is 
run  out  along  the  graduated  beam  to  keep  it  balanced;  in  the 
case  of  some  hydraulic  machines,  such  as  used  for  testing  eye 
bars,  this  may  take  the  form  of  a  mercury  column  which  rises  in 
a  graduated  tube.  While  the  load  is  below  the  elastic  limit,  the 
rider  must  be  moved  forward  at  a  uniform  rate  of  speed,  but  when 
it  is  just  exceeded  the  beam  drops  (drop  of  the  beam,  fall  of  the 
beam),  and  the  corresponding  reading  is  ordinarily  taken  to 
represent  the  elastic  limit  or  more  properly  the  yield  point. 
Testing  machines  must  be  checked  or  calibrated  at  intervals 
to  assure  their  accuracy.  Inaccuracies  may  be  due  to  worn  or 
broken  knife  edges  or  to  dirt  or  grease  interfering  with  the 
sensitiveness,  or  to  the  beam  or  other  part  becoming  bent  or 
distorted.  Calibration  may  consist  in  loading  the  platen  with 
standard  weights,  or  more  frequently,  to  secure  a  greater  range, 
an  arrangement  of  levers  is  provided  which  multiplies  (usually 
twenty  or  twenty-five  times)  the  force  exerted  by  the  known 
load.  The  corresponding  reading  of  the  machine  will  indicate 
its  degree  of  accuracy.  Standardization  is  a  term  sometimes 
employed  to  designate  the  relative  accuracy  with  another 
machine  as  determined  by  the  comparative  results  of  testing  a 
number  of  similar  pieces  on  each. 

The  term  elastic  limit  is  of  such  variable  meaning  that  it  is  well 
to  consider  briefly  its  various  synonyms  and  applications.  T.  D 
Lynch  ("Elastic  Limit,"  Proc.  A.  S.  T.  M.,  1915)  makes  the 
following  observation: 

"We  are  accustomed  to  hear  the  free  use  of  the  following  ten 
distinct  terms,  namely,  (i)  proportional  limit,  (2)  elastic  limit, 
(3)  permanent  set,  (4)  true  elastic  limit,  (5)  apparent  elastic 


470  TESTING 

limit,  (6)  commercial  elastic  limit,  (7)  elastic  limit  by  extenso- 
meter,  (8)  elastic  limit  by  drop  of  beam,  (9)  elastic  limit  by  the 
dividers,  (10)  yield  point. 

"The  first  term,  proportional  limit,  is  very  generally  under- 
stood to  be  at  point  P  on  the  curve  (Fig.  60),  and  the  tenth 
term,  yield  point,  at  the  point  Y,  whereas  the  other  eight  designa- 
tions are  located  on  the  curve  more  or  less  indefinitely  between  the 
points  P  and  F,  depending  upon  the  interpretation  peculiar  to 
different  engineers." 

(It  will  be  noted  that  in  the  following  additional  terms  are 
described.) 

The  following  definitions  have  been  adopted  by  the  A.  S.  T.  M. : 

"Elastic  limit  is  the  greatest  load  per  unit  of  original  cross 
section  which  does  not  produce  a  permanent  set.  (This  determi- 
nation is  rarely  made  in  the  commercial  testing  of  materials.) 

"Proportional  limit  is  the  load  per  unit  of  original  cross  section 
at  which  the  deformation  ceases  to  be  directly  proportional  to  the 
load.  (This  determination  is  rarely  made  in  the  commercial  test- 
ing of  materials.) 

"Yield  point  is  the  load  per  unit  of  original  cross  section  at 
which  a  marked  increase  in  the  deformation  occurs  without 
increase  of  load.  It  is  usual.y  determined  by  the  drop  of  the 
beam  of  the  testing  machine  or  by  the  use  of  dividers." 

Permanent  set  and  true  elastic  limit  are  covered  by  the  definition 
above  for  elastic  limit.  The  apparent  elastic  limit  as  defined  by  a 
French  commission  was  "the  load  per  square  mm.  of  the  original 
section  where  the  deformation  begins  to  increase  sensibly  with 
no  increase  in  the  external  force  applied."  It  will  be  noted  that 
this  agrees  with  the  A.  S.  T.  M.  definition  for  yield  point.  John- 
son proposed  to  extend  its  meaning  in  accordance  with  the 
following  definition:  "The  apparent  elastic  limit  is  the  point  on 
the  stress  diagram  of  any  material  in  any  kind  of  test,  at  which  the 
'  rate  of  deformation  is  50%  greater  than  it  is  at  the  origin." 
This  is  commonly  known  as  the  Johnson  elastic  limit,  and  its 
method  of  computing  is  shown  in  Fig.  61.  Johnson  at  first 
proposed  for  this  the  term  relative  elastic  limit. 

The  Scoble-Johnson  apparent  elastic  limit  or  Scoble's  yield 
point  is  much  the  same  and  is  determined  (by  a  tangent  method) 
by  the  point  of  intersection  of  those  portions  of  the  curve  which 
represent  respectively  a  state  of  perfect  elasticity  and  of  flow. 

Commercial  elastic  limit  is  a  term  loosely  used  in  the  same 
sense  as  yield  point.  Elastic  limit  by  extensometer,  as  its 
name  indicates,  requires  the  use  of  an  instrument  for  determining 
the  rate  of  stretch.  It  may  actually  correspond  with  the  true 
elastic  limit  but  more  often  signifies  something  approximating 
the  proportional  limit.  Elastic  limit  by  drop  of  the  beam  is 
calculated  from  the  reading  on  the  beam  when  it  drops.  The 
elastic  limit  by  dividers  in  its  ordinary  sense  is  determined  by 
fitting  the  points  of  a  pair  of  dividers  in  the  gage  marks  on  the 
specimen,  and  taking  the  reading  when  one  of  the  points  no 
longer  rests  in  its  respective  mark.  A  special  method  known  as 
the  scribe  or  scriber  method  is  carried  out  as  follows:  With  the 


TESTING 


471 


dividers  set  at  the  gaged  length,  and  with  one  of  the  points  resting 
in  the  punch  mark,  a  fine  scratch  is  made  on  the  specimen  with 
the  other;  after  applying  and  removing  the  load  corresponding 
to  the  specified  elastic  limit,  a  line  is  again  scribed.  If  only  one 
line  is  visible  the  material  is  recorded  as  having  exceeded  the 
requirement,  if  a  difference  of  about  0.005"  (f°r  a  2"  gaged 
length)  is  noted,  the  actual  figure  is  recorded;  with  any  greater 
difference  or  yield  the  test  is  considered  to  have  failed.  Primitive 
elastic  limit  is  used  by  Rosenhain  to  indicate  that  the  results 
with  a  material  as  originally  tested  may  be  altered  if  repeated 
after  subsequent  treatment.  Stretch  limit  has  been  used  in  the 
same  sense  as  yield  point.  The  Engineering  Standards  Com- 
mittee (British)  states  that  "a  steel  test  piece  at  the  yield  point 
takes  rapidly  a  large  increase  of  extension  amounting  to  more 
than  3-^po  of  the  gage  length."  This  is  sometimes  referred  to  as 
the  British  or  English  yield  point.  The  yield  stress  corresponds 
to  the  state  for  which  the  stress-strain  curve  becomes  parallel  to 


Strain 


O  Elongation 

FIG.  60. — Stress-deformation  diagram  of  a  tension  test. 
(Lynch,  Proc  A.  S.  T.  M.,  1915.) 

the  axis  of  strain.  At  the  yield  point  the  amount  of  strain 
depends  to  a  certain  extent  on  the  length  of  time  during  which  the 
load  acts  (Smith  and  Wedgwood). 

An  extensometer  is  an  instrument  for  showing  the  amount 
(or  rate)  of  stretch  which  the  specimen  undergoes  during  tensile 
test.  In  one  form  commonly  employed  it  is  called  a  strain  gage. 
A  recording  extensometer  or  autographic  recorder  is  an  instru- 
ment arranged  to  draw  a  curve  automatically.  A  stress-strain 
or  stress -deformation  diagram  is  a  cruve  plotted  with  its  co- 
ordinates as  stress  (load)  and  strain  (deformation)  respectively. 
When  the  elastic  limit  has  been  passed  the  rate  of  stretch  is 
fairly  uniform  with  increase  in  load  until  necking  occurs,  at 
which  point  the  maximum  load  is  registered  on  the  beam  (or 
otherwise),  and  it  is  then  necessary  to  run  the  rider  back  a 
short  distance  if  it  is  desired  to  register  the  load  (breaking  load) 


472. 


TESTING 


at  the  moment  of  rupture;  this  term  is  frequently  used  improperly 
for  maximum  load.  Tonnage  (Eng.)  is  sometimes  used  for 
tensile  strength  (measured  in  gross  tons  per  square  inch).  In 
a  specimen  being  tested,  continued  extension  from  continued 
application  of  the  same  load,  the  time  being  an  important  factor, 


40,000 
30,000 
20,000 
10,000 

D 

•' 

i  —  M 

F     1 

/  cl 

G/ 

^  



Steelll  
fl 

—  i 

.^^—  — 

1 

/^ 

Legend 

20  403     - 

Fr 
l  i 

If 

E 

Tensile 
Yield  I 
Apparc 

Strength 
olnt,  lb.j 
nt  Elasti 

lb.per  sq 
ler  sq.ln. 
Limit,! 

.   73,100 
.  37,650 
18,000    - 

).per  sq.in..  .  .  . 

ill 
I'A 

3           0.1          0.2         0.3         0.4          0.5         0.6 
Elongation  in  2  in.,  percent 

ethod  of  treating  apparent  elastic 

0.7        0.8         0.9 

limit.      (Lynch  — 

Proc.  A.  S.  T.  M.,  1915.) 

is  called  creeping  or  plastic  elongation;  as  it  is  particularly 
noticeable  after  the  elastic  limit  has  been  passed.  It  is  also 
referred  to  as  strain  beyond  the  elastic  limit.  The  reduction  of 
area  is  the  difference  between  the  reduced  area  at  the  point  of 
rupture  (smallest  section)  and  the  original,  and  is  practically 


Note :  The  Gage  Length,  Parallel  Portions  and  Fillets  shall  be  as  shown, 
but  the  Ends  may  be  of  any  Form  which  will  Fit  the  Holders  of 
the  Testing  Machine. 

FIG.  62.— A.  S.  T.  M.  standard  2"  turned  test  piece. 

always  expressed  as  a  percentage;  it  is  nearly  independent  of  the 
gaged  length.     It  may  be  expressed  by  the  formula 


X  ioo 


TESTING  473 

Where  R  —  reduction  of  area  percent; 

a   =  original  cross-sectional  area; 
a'  =  reduced  cross-sectional  area. 

The  test  pieces  are  either  round  or  rectangular  in  cross  section. 
They  may  be  cut  from  material  as  rolled,  such  as  bars,  in  which 
case  they  are  of  sufficient  length  to  provide  space  at  the  ends  for 
gripping.  For  particular  work,  or  if  the  material  is  incon- 
veniently large,  as  in  the  case  of  forgings  or  other  heavy  objects, 
they  are  machined  down  to  provide  a  middle  portion  of  parallel 
section  connected  by  fillets  with  collars  or  enlarged  ends  for 
holding  in  the  machine.  Upon  the  parallel  section  is  laid  off  the 
length  (gage  length,  gaged  length)  in  which  the  elongation  is  to 
be  measured,  usually  indicated  by  prick-punch  marks  (pop  marks, 
datum  points).  In  this  country,  for  plates  or  similar  flat  material 
permitting  of  having  two  of  the  surfaces  rolled,  the  specimen  is 
usually  rectangular  (the  other  sides  being  machined  or  milled), 
with]£a  gage  length  of  8",  the  thickness  being  that  of  the 


About  3"— J  ,  *     Ljg™ 

v.f         !     Not  less  than 


-About  18  —  - 


FIG.  63.— A.  S.  T.  M.  Standard  8"  flat  test  piece. 

given  material;  for  turned  specimens,  cut  from  large  pieces,  the 
gage  length  is  commonly  2",  with  diameter  of  %".  The  standard 
test  pieces  of  the  American  Society  for  Testing  Materials  are 
shown  in  Figs.  62  and  63.  The  effect  of  form  of  the  test  piece 
must  be  taken  into  consideration,  particularly  as  regards  the 
elongation.  It  has  been  found  approximately  true  that  the  same 
results  will  be  secured  by  two  test  pieces  if  they  are  of  identical 
dimensions  or  of  similar  form;  this  is  known  as  Barba's  law  or  the 
law  of  proportionality,  or  similarity.  This  is  given  by  the  formula 


Where  P  is  the  proportionality;  /  is  the  gaged  length;  and  a  is  the 
cross-sectional  area.  The  values  of  P  in  various  standard  test 
pieces  are  given  in  the  following  table: 


474 


TESTING 


Comparative  Requirements  for  Elongation  for  Different 

Test  Speicmens 

Name  Formula  Size  Comparative 

elongation, 


u.  s.. 

•M 

t 

French  .  .  . 

a 

i 

=  66.67 
=  8,) 

2" 


(20) 


(18) 


Italian . . 


German . . 


100  mm.  X  13 . 8  mm.  0 

3.94"  Xo.543"0  (12) 

5"Xo.5" 

loomm.  X  10  mm.  </>       (10) 


n-3 


3.94"  X  0.349"  0 
100  mm.  X  10  mm. 


(10) 


3.94"  X  0.394"^ 

/    =  gage  length 

a   =  cross-sectional  area 

D  =  diameter. 

NOTE. — Figures  in  parenthesis  (    )  are  estimated. 

Owing  to  the  effect  of  necking  with  local  increase  in  the  elonga- 
tion, it  is  customary  to  eliminate  specimens  which  have  not 
broken  within  the  middle  third  of  the  gage  length;  Martens  has 
shown  that  in  some  cases  the  elonagtion  for  specimens  breaking 
near  one  end,  as  compared  with  those  breaking  in  the  middle,  has 
been  lowered  as  much  as  20%.  It  is  pointed  out  by  Martens 
(Resistance  of  Materials,  Henning's  trans.,  pp.  121-2)  that  elonga- 
tion really  consists  of  two  parts:  (a)  the  extension  (nearly 
uniform)  before  local  contraction  or  necking  occurs,  and  (b)  the 
local  elongation  due  to  such  necking.  He  gives  the  following 
formula  for  determining  the  elongation  for  any  gage  length  in  the 
case  of  material  of  known  properties: 


e%  =  100 


Where  e  =  elongation,  0  =  extension  of  unit  length  up  to  the 
moment  of  local  contraction,  ec  —  extension  during  local  con- 
traction, la  =  gage  length.  This  is  of  course  not  practicable  for 
ordinary  work,  and  a  direct  determination  is  the  only  accurate 
method  for  obvious  reasons.  Prof.  Unwin  also  showed  by  ex- 
periment for  turned  test  pieces,  that  if  the  value  obtained  by 
dividing  the  gaged  length  by  the  diameter  was  constant,  the 


TESTING 


475 


elongation  would  be  approximately  constant.  In  the  case  of 
material  like  steel,  the  necking  down  has  a  material  effect  on  the 
elongation;  consequently,  the  difference  in  gaged  length  is  more 
noticeable  with  pronounced  local  necking  which  occurs  in  the 
softer  grades  and  especially  in  heat  treated  and  alloy  steels. 
With  rectangular  specimens,  up  to  a  certain  point,  the  greater 
the  ratio  of  width  to  thickness  the  higher  the  elongation.  As 
regards  other  tensile  properties,  the  strength,  elastic  limit,  and 
reduction  of  area  are  not  so  greatly  affected.  The  strength  and 
elastic  limit  are  increased  by  a  sudden  change  of  section,  particu- 
larly where  the  specimen  is  short,  such  as  a  collar  or  shoulder 
without  fillets  or  where  a  notch  is  cut  in  the  piece.  For  a  com- 
plete discussion  treatises,  such  as  those  by  Martens  or  Unwin, 
must  be  consulted. 

The  speed  of  testing,  i.e.,  the  rate  at  which  the  machine  is 
operated,  principally  affects  the  determination  of  the  yield 
point.  The  speeds  recommended  by  the  A.  S.  T.  M.  are  as 
follows : 


Maximum  Crosshead  Speed  for 

Testing  Machine  in 

Specified  Minimum  Ten- 
sile  Strength  of  Material 

Gage 
Length 

Determining 

Yield  Point 

Tensile 
Strength 

Lb.  —  sq.  in. 

In. 

In.  per  min. 

In.  per  min. 

80,000  or 

8 

0.50 

2.O 

under 

2 

2.00 

6.0 

Over  80,000 

8 

0.25 

I.O 

2 

0.50 

2.0 

After  rupture  the  reduced  dimensions,  at  the  point  of  rupture, 
are  measured  for  the  purpose  of  determining  the  reduction  of 
area;  the  two  portions  are  then  fitted  accurately  together  and, 
from  the  increase  in  distance  between  the  punch  marks,  the 
elongation,  either  actual  or  as  a  percentage,  is  calculated. 

It  is  a  well  recognized  fact  that,  for  material  of  the  same  grade 
and  treatment,  as  the  strength  increases  the  ductility  decreases 
and  vice  versa.  This  is  sometimes  covered  in  specifications  by 
the  proportion  or  inverse  ratio  (which  is  approximately  correct 
within  certain  limits)  between  them.  Requirements  according 
to  this  would  be  stated,  for  example,  elongation,  not  less  than 


1,500,000 


;  and  reduction  of  area,  not  less  than 


2,400,000 


A  device,  known  as' a  weigh  bar,  is  sometimes  employed  where 
a  completely  equipped  testing  machine  is  not  available.  This  is 
simply  a  bar  of  high  elastic  limit  and  large  section  which  is  cali- 
brated as  to  extension  (within  its  elastic  limit)  for  different 


476  TESTING 

weighed  loads.  The  specimen  to  be  tested  is  attached  to  one 
end  and  the  free  end  of  each  attached  to  any  machine  capable 
of  exerting  tension.  By  measuring  the  extension  on  the  weigh 
bar  during  the  test  a  simple  calculation  will  indicate  the  actual 
load  applied. 

Tensile  properties  may  also  be  determined  approximately 
by  Brinell's  ball-testing  method  (see  below). 

Compression  tests  may  usually  be  made  on  the  same  type 
of  vertical  machine  as  used  in  tensile  tests.  As  explained  in 
Physical  Properties  the  elastic  limit  is  the  true  measure  of 
strength  of  a  ductile  body  owing  to  the  flowing,  with  consequent 
increase  of  section,  which  results  when  this  limit  is  exceeded. 
It  is  checked  by  a  measuring  device  termed  a  compressometer 
similar  to  an  extensometer.  A  piezometer  is  an 'instrument  to 
determine  directly  the  modulus  of  compression.  Compression 
tests  are  also  used  to  determine  ductility  in  which  case  they  con- 
sist in  reducing  a  piece  (either  hot  or  cold)  a  certain  proportion 
of  its  original  height. 

Hammer  tests,  or  forging  tests,  are  used  to  determine  the 
malleability  of  metal;  the  sample  is  hammered  (hot  or  cold) 
usually  to  a  given  fraction  of  the  original  thickness.  In  making 
a  scarfing  test  one  edge  of  a  flat  piece  is  hammered  down  at 
an  angle,  and  no  cracks  must  result.  Smithy  tests  (Eng.) 
usually  consist  in  heating  a  piece,  splitting  it  a  certain  distance, 
and  bending  the  ends  outward  into  a  ramshorn  (ramshorn 
test);  a  hole  may  also  be  punched  near  the  cut  and  drifted. 

Bend  (bending)  tests  are  static  tests  to  determine  the  ductility, 
and  to  a  certain  extent  the  toughness,  of  material,  by  bending  a 
specimen  over  on  itself,  usually  180°  but  in  some  cases  90°,  in  the 
former  case  flat  (for  small  and  soft  material)  or  in  either  case 
with  a  given  curvature  at  the  bent  portion,  frequently  expressed 
as  around  a  bar  of  stated  diameter,  D,  or  as  a  function  of  the 
thickness,  t,  of  the  piece,  as  180°  D  =  $t.  The  specimen  is 
required  to  meet  this  test  without  evidence  of  cracking  on  the 
outside  of  the  bent  portion  (where  the  strain  is  greatest) ;  in  some 
cases,  particularly  relatively  brittle  or  high  elastic  material  such 
as  springs,  the  test  may  be  carried  on  until  rupture  occurs  when 
the  angle  is  measured  by  some  form  of  protractor.  A  nick  bend 
test  is  where  a  nick  or  notch  is  cut  transversely  in  the  specimen, 
usually  on  the  outside  of  where  the  bend  is  to  occur,  sometimes  on 
both  sides  or  all  around.  This  is  used  practically  only  in  connec- 
tion with  fire  box  steel,  when  it  is  frequently  referred  to  as 
homogeneity  test.  Bends  may  be  of  the  following  kinds: 

1.  Cold   bend:  specimen   as   manufactured   with   no   subse- 
quent treatment  except  shearing  or  machining. 

2.  Hot  bend:  Specimen  heated  to  a  cherry  red,  and  tested 
at  that  temperature. 

3.  Quench  bend  (rarely  called  temper  test):  specimen  heated 
to  a  cherry  red  and  quenched  in  water  before  bending. 

A  test  for  the  toughness  and  elasticity  of  wire,  sometimes 
called  snarling,  consists  in  bending  and  twisting  it  backward 
and  forward. 


TESTING  477 

Transverse  tests  or  deflection  tests  are  usually  employed  in 
determining  the  elastic  limit  (and  the  transverse  strength  if  the 
material  breaks  before  bending  too  far)  for  such  objects  as  leaf 
springs,  carriage  axles,  etc.  It  consists  in  supporting  the  piece 
on  bearings  spaced  a  certain  distance  apart  and  applying  the  load 
at  the  middle;  the  stresses  with  corresponding  strains  (deflec- 
tions) are  then  plotted,  including  any  permanent  set  after  each 
successive  load  has  been  applied  and  removed.  A  somewhat 
similar  test,  known  as  a  dead  weight  test  or  loading  test,  is 
occasionally  applied  (e.g.]  to  rails;  a  full-size  specimen  is  laid  on 
supports  a  stated  distance  apart  and  has  to  sustain  a  given  load 
a  certain  length  of  time  without  any  permanent  deflection  after 
the  load  has  been  removed.  "The  modulus  of  rupture  has  a 
conventional  meaning.  It  expresses  in  pounds  per  square  inch 
the  apparent  maximum  fiber  stress,  tension  or  compression,  of  a 
member  transversely  loaded,  as  it  is  just  on  the  point  of  breaking  ; 
the  stress  being  calculated  by  the  common  beam  theory,  with  its 
three  important  assumptions  which  are  known  to  be  inaccurate 
above  the  elastic  limit"  (L.  H.  Fry). 

Shearing  tests  consist  in  determining  the  stress  required  to 
shear  or  cut  material,  such  as  plates  or  bars;  in  some  cases  by 
applying  shearing  stresses  to  the  rivets  in  riveted  pieces.  It  is 
expressed  per  unit  of  area.  Punching  tests  are  another  form  of 
shearing  tests,  and  usually  consist  in  punching  holes  in  a  sample 
to  determine  the  suitability  of  the  material  for  this  kind  of  work. 
It  is  rarely  required  to  determine  the  actual  resistance  per  unit 
of  area.  In  connection  with  this  a  drift  test  is  sometimes  speci- 
fied. This  is  performed  by  enlarging  a  punched  hole  a  certain 
amount,  without  causing  any  cracks,  by  driving  through  it  a 
tapered  pin.  A  torsion  test  also  involves  shear.  It  consists 
in  twisting  the  specimen,  the  actual  load  and  the  number  of 
circular  degrees  being  measured  for  the  elastic  limit  and  the 
ultimate  strength  respectively.  The  elastic  limit  may  be  checked 
by  a  torsiometer  similar  to  an  extensometer.  The  stress  is  a 
function  of  the  cube  of  the  diameter  or  thickness.  In  general 
results  torsion  tests  agree  closely  with  tensile  tests  although  the 
actual  respective  figures  may  not  be  directly  comparable  except 
for  standard  test  specimens. 

For  the  latest  information  on  detailed  requirements  and  stand- 
ard specifications  the  Proceedings  and  Year  Book  of  the  Ameri- 
can Society  for  Testing  Materials  should  be  consulted. 

Hardness  Tests.  —  Static  indentation  or  pressing-in  method. 
Brinell's  ball-testing  method  consists  in  measuring  the  indenta- 
tion produced  by  forcing  into  the  material  a  hardened  steel  ball 
of  a  definite  size  (usually  10  mm.  in  diameter)  under  a  standard 
load  (usually  500  Kg.  for  soft  materials  such  as  brass,  and  3000 
Kg.  for  hard  materials  such  as  steel).  From  the  size  of  the 
impression  the  hardness  number,  H,  can  be  calculated  according 
to  Brinell's  formula  : 


irD  (D  —  \D*  —  d*) 


478  TESTING 

"  W  =  load  in  Kg.;  D  =  diameter  of  ball  in  mm.;  d  =  diameter  of 
impression  in  mm.  Benedick's  formula,  for  the  same  purpose  is 
as  follows: 


L  —  load  in  Kg. ;  A  —  superficial  area  of  concave  surface  of  indenta- 
tion; p  =  radius  of  ball.  In  the  table  given  below  are  the  approxi- 
mate relations  between  hardness  number  and  tensile  strength. 
Guillery's  method  is  similar  to  Brinell's,  consisting  in  measuring 
the  indentation  produced  by  a  small  ball  by  the  pressure  exerted 
by  Belleville  springs  under  a  determined  deflection.  Foeppl's 
method  consists  in  testing  the  metal  or  substance  with  itself; 
two  pieces  are  specially  prepared  and  pressed  together  under  a 
constant  load,  the  indentation  thus  produced  varying  inversely 
as  the  hardness.  Ludwik's  method  or  cone  test  depends  upon  the 
impression  produced  by  forcing  in,  under  constant  load  a  circular 
cone  with  90°  angular  opening.  The  Amsler-Laffon  machine 
employed  a  90°  rounded  cone  which  is  forced  into  the  material 
under  constant  load  and  the  depth  of  impression  shown  on  a 
graduated  scale  by  a  needle  indicator. 

Dynamic  Indentation  or  Driving -in  Method. — Shore's  method 
depends  upon  the  use  of  an  instrument. known  as  a  scleroscope 
which  consists  essentially  of  a  small  diamond-pointed  hammer 
falling  freely  in  a  graduated  glass  tube  from  a  constant  height 
on  the  surface  of  the  object,  the  hardness  (or  rather  the  elastic 
quality  termed  the  coefficient  of  restitution)  of  which  is  measured 
by  the  height  of  the  rebound.  By  multiplying  the  scleroscope 
number  by  6  an  approximate  conversion  to  the  Brinell  number  is 
secured;  it  must  be  borne  in  mind,  however,  that  exactly  the 
same  qualities  are  not  determined  as  one  test  is  dynamic  while 
the  other  is  static.  The  Keen  impact  ball  tester  consists  of  a 
hardened  ball  secured  at  the  end  of  a  rod;  this  rod  serves  as  a 
guide  for  a  weight  falling  from  a  height  of  about  3  feet,  the  blow 
which  it  delivers  serving  to  force  the  ball  into  the  material  upon 
which  it  rests.  The  amount  of  impression  is  then  measured. 
The  Brinell  meter  depends  upon  the  comparison  with  a  standard 
specimen  by  producing  an  impression  by  the  blow  from  a  hand 
hammer.  The  Pellin  hardness -testing  machine  is  a  ball  held 
in  a  weighted  frame  which  is  allowed  to  fall  on  the  sample,  and 
the  diameter  of  the  impression  is  measured.  In  Fremont's 
method  a  weight,  with  a  specially  shaped  point,  is  allowed  to  fall 
on  the  object,  and  the  indentation  is  measured.  The  Ballantine 
method  is  carried  out  with  an  instrument  in  which  a  cylinder  of 
lead  is  supported  on  a  cylindrical  anvil,  the  lower  end  of  which  is 
pointed  and  rests  upon  the  material  to  be  tested.  A  weight  or 
hammer  is  allowed  to  fall  on  the  lead  cylinder,  and  acts  through 
it  upon  the  anvil  which  is  driven  into  the  sample.  The  deforma- 
tion of  the  lead  is  inversely  as  the  hardness  of  the  sample. 

Abrasive  Hardness  or  Surface  Scratching. — Moh's  scale  was 
devised  to  determine  the  relative  hardness  of  mineral  substances, 
based  on  the  fact  that  an  object  will  scratch  one  of  equal  or  less 
hardness,  but  not  one  which  is  harder  (see  page  480). 


TESTING 


479 


«*£ 


. 

" 


vn  o  v 
go,  a 


.n 
c  0 
M  OT 


.g  K-i 


oooooooooooooo 
oooooooooooooo 

<N  t^  N  oo  >rj  w  oo  vO  •*  N  O  Oioo  t- 


O  r~  •*  M  oo  O  •<*  w  00 


O<  I-  »/>  PO  w  0> 

^ 


iovO\O  t^  t^oo  00  O>  Oi 


ot/sotooiflOi^oiooirtOio 

ro'^^f^J'to  100  ^O  r-  r^oo  oo  O\  C\ 


OOOOOOOOOOOOOOOOOOOO 
OOOOOOOOOOOOOOOOOOOO 
M  rooo  vO  oo  cs  oo  r~-oo  M  \o  ro  N  ^  rj-oo  ro  Ov  r^  10 


PO  r^  N  i>  PO 


M  O  OO  t^O  IO  Tj-  p<5  (N  H  O 


OvOO  r^ 
NINN 


fO  ro  1^5  r«5  (*3  ro  ro  PO  fO  f«3  PO  fO  ro 


OOOOOOOOOOOOOOOOOOOO 
OOOOOOOOOOOOOOOOOOOO 

10  C<  M   M   PO\O  Ovoi-ioO»flttPO<NPOPO"lOOOw 


OiOO  00  00  t~- 


X 


o    C 
*        >H 


M    .g 
~    ST 


s 

c 

O 
u 

O 

PJ{     ^ 
W      o 

8  I 


480  TESTING 

r.  Talc. 

2.  Rock  salt. 

3.  Calcite. 

4.  Fluorspar. 

5.  Apatite. 

6.  Orthoclase. 

7.  Quartz. 

8.  Topaz. 

9.  Corundum. 
10.  Diamond. 

Behren's  scale  adapted  for  metals,  and  based  on  the  use  of 
sharp-pointed  needles  for  testing,  is  as  follows: 

1 .  o,  Lead. 
1.7,'  Tin. 

2 .  o,  Tin  with  iron, 
i .  5  to   2.2,         Hard  lead. 
2.5,                       Zinc. 

3.0,  Copper. 

2.1,  Brass  wire. 

3.3,  Gun  metal  (bronze). 

3.5,  Bronze  with  12%  tin. 

3.7,  Bronze  with  18%  tin. 

3 . 7  to  3 . 9,  Iron  wire. 

4 .  o,  Needles  tempered  yellow. 

5 .  o,  Needles  tempered  blue. 

5 .  o  to  5 . 5,  Sewing  needles. 

6 .  o,  Drill  steel  tempered  yellow. 
6 . 2  to  6 . 5,          Chrome  steel. 

7.0  to  7. 3,          Ferro-chrome. 

Certain  of  the  materials,  at  least,  are  too  variable  to  make  this 
scale  anything  more  than  approximate. 

Marten's  test  (hardness  tester)  depends  upon  the  width  of 
scratch  produced  by  dragging  across  the  surface  of  the  material 
a  diamond  point  under  a  definite  load.  .Turner's  method  is 
similar  to  the  above  except  it  depends  upon  the  weight  necessary 
to  produce  a  visible  scratch;  the  instrument  employed  is  termed  a 
sclerometer.  Bauer's  method  is  based  on  the  depth  of  penetra- 
tion of  a  drill  operating  under  constant  conditions  of  speed  and 
pressure.  -  Keep's  hardness  test  is  similar  to  Bauer's,  an  auto- 
graphic record  being  taken  of  the  progress  of  the  drill.  In 
Jagger's  method  an  instrument  called  a  microsclerometer  is  used. 
This  is  a  small  weighted  drill  provided  with  a  diamond  point,  and 
the  depth  of  the  hole  produced  by  drilling  for  a  certain  length  of 
time  (at  constant  speed)  is  measured.  It  is  intended  to  be  used 
in  connection  with  a  microscope  for  determining  the  relative 
hardness  of  the  microscopic  constituents  of  metals.  Wearing 
tests  may  take  the  form  of  abrading  a  specimen  under  constant 
load  by  means  of  a  grinding  wheel  or  revolving  disk  covered  with 
a  suitable  abrasive.  Methods  employed  by  Saniter,  Stanton 
and  Norris  consist  essentially  in  subjecting  cylindrical  specimens 
to  a  rubbing  action  by  rotating  them  against  other  material. 


TESTING  481 

Dynamic  Tests. — Those  in  which  the  load  is  suddenly  or  re- 
peatedly applied,  as  opposed  to  static  tests  where  the  load  it 
gradually  applied.  They  are  usually  divided  into  (a)  impact 
tests  where  the  test  specimen  is  subjected  to  a  blow,  and  (b) 
endurance  tests  where  the  stresses  are  repeatedly  applied  either 
in  the  same  or  in  alternate  directions.  They  are  used  to  deter- 
mine the  toughness  (or  absence  of  brittleness)  of  material, 
particularly  those  going  into  moving  parts  which  are  subjected 
to  such  conditions  in  actual  service.  The  tests  may  be  carried 
out  on  full-size  objects,  such  as  car  axles  or  pieces  of  rail,  or  on 
small  sections  cut  out  and  especially  prepared. 

Impact  Tests. — Also  termed  shock  tests,  percussion  tests, 
falling  weight  tests,  drop  tests,  drop  weight  tests,  hammer  tests, 
or  impact  crushing  tests.  Johnson  says  "The  unit  of  measure, 
in  impact  tests  is  the  foot-pound  (or  the  kilogrammeter) .  This 
energy  cannot  be  measured  in  pounds,  and  no  scheme  of  equiva- 
lents can  be  devised  between  the  foot-pound  units  of  an  impact 
test  and  the  pound  units  of  a  static  test,  although  this  has  often 
been  attempted.  There  is  no  relation  between  the  resistance 
to  shock  and  the  resistance  to  a  static  load,  since  there  is  no 
relation  between  the  total  area  of  a  stress  diagram  and  its  stress 
coordinate.  The  attempt  which  is  often  made,  therefore,  to 
equate  these  two  kinds  of  resistance  is  as  foolish  as  the  ancient 
practice  of  estimating  the  discharge  of  stream,  or  aqueduct,  or 
pipe,  from  its  cross  section  alone."  In  bridge  design,  for  example, 
the  coefficient  of  impact  is  a  number  by  which  the  calculated 
static  stresses  are  multiplied  in  order  to  take  care  of  the  increase 
to  be  allowed  for  impact  stresses.  The  specimen,  either  full-size 
or  of  reduced  section,  rests  on  supports  a  certain  distance  apart 
and  the  hammer,  tup  or  bob  strikes  it  midway.  The  specimen 
may  be  required  to  withstand  one  or  more  blows  without  rupture, 
or  the  energy  (striking  or  impact  energy)  may  purposely  be 
made  more  than  sufficient  to  effect  rupture  (single-blow-test), 
in  which  case  the  residual  energy  is  measured,  the  difference 
representing  the  absorbed  energy,  indicating  the  energy  of 
deformation,  work  of  deformation,  or  specific  work  of  rupture. 
Car  axles  are  tested  on  a  drop  test  machine,  ordinarily  resting  on 
supports  at  a  distance  of  3  feet  between  centers,  with  a  tup  weigh- 
ing 2240  pounds  falling  freely  from  a  height  which  varies  accord- 
ing to  the  size  of  the  axle;  they  are  turned  180°  about  their  axis 
after  the  first,  third,  fifth,  etc.,  blow,  according  to  the  number 
which  must  be  withstood.  Usually  the  deflection  at  the  center, 
measured  from  a  straight  line  between  the  journal  collars,  must 
not  exceed  a  prescribed  maximum  after  the  first  blow.  Rails 
are  tested  in  a  similar  manner,  usually  resting  on  their  base; 
a  deflection  requirement  is  also  customary.  In  some  cases  the 
ductility  (ductility  test)  is  determined  by  measuring  the  increase 
between  marks  previously  placed  on  the  base  (or  lower  portion) ; 
a  minimum  percentage  must  be  shown.  Cast  iron  car  wheels 
are  sometimes  tested  on  a  wheel  breaker,  resting  flange  down  on 
three  supports  spaced  120  degrees  apart,  the  tup  falling  centrally 
on  the  hub,  and  a  certain  number  of  blows  to  be  withstood 
31 


482  TESTING 

without  rupture.  A  special  form  of  impact  test  is  what  is  known 
as  proof  testing.  This  consists  in  subjecting  all  the  objects, 
before  being  accepted  or  placed  in  service,  to  a  blow  less  than  will 
produce  any  permanent  distortion.  This  may  take  the  form  of  a 
modified  axle  test  or  of  allowing  the  object  itself  to  drop  from  a 
specified  height;  it  may  also  be  struck  with  a  hand  hammer  or 
sledge  (peening  test).  The  specimen  is  frequently  cut  away  in 
some  form  of  notch  at  the  point  where  it  is  intended  to  break  it. 
The  resistance  to  rupture  is  therefore  sometimes  termed  notch 
toughness.  Owing  to  the  variable  results  due  to  the  different 
forms  of  notch  and  also  the  fact  that  it  is  very  difficult  to  insure 
uniformity,  a  plain  bar  is  preferred  by  many;  Me  Adam,  for 
example,  recommends  a  plain  bar  to  be  sheared  by  the  impact 
applied  by  a  pendulum  hammer  (impact  shear  test);  this  intro- 
duces a  single  kind  of  stress  instead  of  a  combination,  and  in 
addition  to  avoiding  slight  variables  in  the  notch  is  much  simpler 
to  carry  out. 

Of  the  tests  producing  rupture  one  of  the  best  known  is  the 
Charpy  test,  which  employs  a  machine  of  that  name,  also  termed 
the  Charpy  pendulum  hammer;  the  difference  in  swing  (number 
of  degrees),  after  passing  the  lowest  point,  when  a  specimen  is 
broken  from  what  would  have  occurred  without,  is  the  measure 
of  the  absorbed  energy.  The  Fremont  machine  is  similar  in 
principle,  the  tup,  however,  falling  vertically,  and  the  residual 
energy  being  measured  by  means  of  a  scale  and  indicator.  Other 
similar  tests  of  the  one-blow  method  are  those  of  Russell,  Izod, 
and  Seaton;  tests  of  the  many-blow  method  include  those  of 
Breuil,  Yarrow,  Seaton  and  Jude,  Brinell  and  Wahlberg,  Ruelle, 
and  Stanton. 

Endurance  Tests.— Also  termed  fatigue  tests,  vibratory  tests  or 
repetitive  stressing.  In  Wohler's  tests  the  specimen  was  not 
loaded  beyond  the  elastic  limit  and  the  stresses  might  be  applied 
all  in  one  direction  (from  zero  to  a  maximum,  or  from  one  load 
to  a  greater  load),  or  first  in  one  direction  and  then  in  the  other 
(as  from  tension  to  compression).  The  number  of  repetitions  or 
alternations  of  different  stresses  to  produce  rupture  served  to 
indicate  the  fatigue  properties  of  the  material  in  question. 
Where  an  infinite  number  of  repetitions  would  be  necessary  with 
a  certain  stress,  below  that  figure  is  sometimes  termed  the  Wohler 
range  of  entire  resistance  to  fatigue.  The  specimens  are  usually 
not  stressed  beyond  the  elastic  limit,  although  in  some  forms  of 
test  such  is  the  case.  The  piece  may  be  vibrated  by  a  recipro- 
cating or  rotational  movement.  Machines  and  tests  have  been 
devised  for  alternate  bending  by  Stead,  Sankey,  and  Amsler- 
Laffon;  for  rotational  stresses  by  White  and  Souther;  for  vibra- 
tion by  Arnold,  etc. 

Miscellaneous  Methods.— Ballistic  tests,  also  termed  firing 
tests  and  proof  tests,  are  employed  in  connection  with  armor 
plate  and  projectiles.  The  armor  plate  must  withstand  the 
attack  of  the  prescribed  number  of  standard  projectiles,  and  the 
projectiles,  depending  upon  their  type,  must  meet  various  condi- 
tions, such  as  the  penentration  of  a  certain  thickness  of  armor, 


TESTING  483 

break  up  on  detonation  into  a  rninimum  number  of  fragments 
(fragmentation  test)  etc.,  in  addition  to  resisting  deforma- 
tion while  in  the  gun.  It  was  at  one  time  common  practice  to 
take  a  sample  billet  from  each  heat  and  roll  it  down  into  a  round 
of  about  %"  in  diameter,  from  which  pieces  were  taken  for  tensile 
tests  which  were  considered  as  indicative  of  the  qualities  of  the 
other  material  produced.  This  was  known  as  the  billet  test, 
but  has  been  abandoned  as  not  truly  representative.  A  compara- 
tor is  an  instrument  for  determining  the  coefficient  of  expansion 
of  solids  by  comparison  with  a  standard.  A  conductometer  is 
an  instrument  for  determining  conductivity  for  heat,  electricity, 
etc.  A  dilatometer  is  an  instrument  to  measure  changes  in 
volume  on  heating  or  cooling. 

Ductility  Tests.— In  addition  to  those  described  elsewhere, 
the  following  might  be  mentioned.  A  British  method  is  to 
specify  the  sum,of  the  elongation  (in  percent)  and  the  tensile 
strength  (in  gross  tons)  to  be  not  less  than  a  given  value;  for 
example,  with  a  range  in  tensile  strength  of  35  to  40  tons  the 
actual  tensile  strength  plus  the  elongation  (percent  in  2") 
must  be  not  less  than  60.  The  Tetmayer  formula  (or  a  similar 
requirement)  sometimes  found  in  foreign  specifications,  is  that 
the  product  of  the  elongation  (in  millimeters)  in  a  length  of  200 
millimeters,  and  the  tensile  strength  (in  kilograms  per  square 
millimeter)  must  equal  or  exceed,  say  750.  A  ductilimeter  is  the 
term  sometimes  applied  to  an  instrument  to  measure  ductility. 
A  dynamometer  is  an  instrument  to  measure  the  amount  of  work 
developed  as  in  the  case  of  an  engine,  motor,  etc.  For  example, 
a  form  known  as  a  Prony  brake  (brake  test)  to  determine  the 
horse  power  which  an  engine  can  develop  consists  in  clamping  a 
frictional  brake  to  the  fly  wheel  or  shaft  so  tightly  that  it  can 
barely  revolve;  the  torque  is  counterbalanced  by  weights. 
Keep's  tests  were  suggested  by  him  as  a  method  for  a  mechanical 
analysis  of  the  properties  of  cast  iron  based  on  the  variations  in 
the  amount  of  shrinkage  caused  by  different  amounts  of  silicon 
present.  The  nick  and  break  test  (fracture  test)  sometimes  used 
for  rails,  consists  in  nicking  and  breaking  a  piece  for  the  purpose  of 
detecting  any  internal  flaws  or  defects  by  a  visual  examination. 
The  oncosimeter  is  a  special  form  of  instrument  in  which  the 
force  acting  on  a  metal  ball  suspended  in  a  molten  metal  by  a 
spiral  spring  is  measured;  in  this  way  it  was  shown  that  gray  cast 
iron  and  bisumth  expand  on  solidification,  while  copper,  silver, 
lead,  tin,  and  zinc  contract  (Desch).  A  test  referred  to  as  a 
ringing  test,  resonance  test,  or  sonority  test,  consists  in  striking 
an  object  (sometimes  while  suspended)  with  a  small  hammer  or 
piece  of  metal  to  determine  by  the  sound  produced  whether  any 
internal  flaws  or  unsoundness  exist.  The  schiseophone  was  a 
modification  of  Prof.  Hughes'  induction  balance,  designed  for 
detecting  flaws  in  rails,  etc.  A  core  is  reciprocated  longitudinally 
within  a  coil  and  caused  to  strike  the  object.  A  continuous 
current  from  a  battery  is  sent  through  this  coil,  which  is  connected 
with  one  of  the  coils  in  the  induction  balance.  The  other  coil 
on  the  balance  is  adjusted  to  reduce  or  abolish  the  sound  in  the 


484     TESTING  MACHINE— THERMOELECTRIC  COUPLE 

telephone.  When  the  core  gtrikes  the  object  near  a  flaw,  it  is 
claimed  that  the  difference  in  the.  quality  of  the  sound  is  readily 
detected.  A  shrinkage  test  (as  applied  to  rails)  is  a  requirement 
that,  after  hot  sawing,  the  shrinkage  shall  not  exceed  a  specified 
amount  varying  with  the  ordered  (cold)  length  and  the  weight 
or  design  of  the  section.  The  spark  test  is  a  method  worked  out 
by  J.  F.  Keller  for  distinguishing  different  metals,  particularly 
different  types  and  grades  of  iron  and  steel,  by  the  appearance 
and  nature  of  the  spark  thrown  off  when  a  sample  is  held  against 
a  grinding  wheel,  or  produced  by  similar  means.  The  stremma- 
tographis  an  instrument  devised  by  Dr.  P.  H.  Dudley  to  measure 
the  stresses  and  record  the  effect  on  the  rails  caused  by  a  passing 
train.  Cast  iron  is  usually  tested  transversely  with  an  arbitration 
bar  (designed  and  advocated  by  the  American  Foundrymen's 
Association),  i%"  in  diameter  and  15"  long,  which  is  cast  from  a 
sample  of  the  metal  in  a  special  mold  under  prescribed  conditions. 
In  testing,  the  supports  are  12"  apart,  the  load  applied  at  the 
middle,  and  the  deflection  at  rupture  (cross  breaking  strength) 
noted. 

Testing  Machine. — See  page  469. 

Tetarto  Prismatic  System.— Of  crystallization:  see  page  120. 

Tetmayer  Formula. — See  page  483. 

Tetrad. — See  page  86. 

Tetragonal  System. — Of  crystallization:  see  page  120. 

Tetratomic. — See  page  87. 

Tetravalent. — See  page  86. 

Texture. — See  page  125. 

Thalpotassimeter. — See  page  210. 

Theodossief  Process. — See  page  230. 

Theoretical  Chemistry. — See  page  81. 

Thermal  Analysis. — See  page  284. 

Thermal  Capacity. — See  page  201. 

Thermal  Chemistry. — See  page  82. 

Thermal  Conductivity. — See  page  200. 

Thermal  Crack.— See  Crack. 

Thermal  Equilibrium. — See  page  327. 

Thermal  Metamorphism. — See  pages  122  and  271. 

Thermal  Method.— Of  determining  critical  points:  see  page  265. 

Thermal  Refining. — See  page  213. 

Thermal  Resistance. — See  page  200. 

Thermal  Stability. — See  page  275. 

Thermal  Transformation. — See  page  326. 

Thermal  Treatment. — Heat  Treatment. 

Thermal  Unit. — See  page  199. 

Thermally  Metastable  State.— See  page  281. 

Thermit  (Thermite);  Process;  Weld.— (i)  For  reducing  metals: 
see  Goldschmidt  Process;  (2)  for  producing  sound  ingots:  see 
page  6 1 ;  (3)  for  welding:  see  page  504. 

Thermochemistry. — See  page  82. 

Thermo-couple. — See  page  208. 

Thermo -elastic  Properties. — See  page  330. 

Thermoelectric  Couple. — See  page  208. 


THERMOELECTRIC— THWIMG  PYROMETER      485 

Thermoelectric    Method. — For    determining    critical    points:  see 

page  266. 

Thermoelectric  Pair. — See  page  208. 
Thermoelectric  Pyrometer. — See  page  208. 
Thermoelectric  Telescopes. — See  page  207. 
Thermo -element. — See  page  208. 
Thermogage,  Morse. — See  page  207. 
Thermograph. — See  page  205. 
Thermolabile. — See  page  204. 
Thermolysis. — See  page  82.  " 
Thermo -magnetic  Selector. — See  page  210. 
Thermo-metallurgy. — See  page  82. 
Thermometer. — See  page  205. 
Thermometric  Conductivity. — See  page  200. 
Thermometric  Heat. — See  page  199. 
Thermometric  Scales. — See  page  204. 
Thermometrograph. — See  page  205. 
Thermometry.— See  page  205. 
Thermoneutrality. — Law  of:  see  page  201. 
Thermophone,  Wiborgh's. — See  page  210. 
Thermopile. — See  page  207. 
Thermoradiometer. — See  page  205. 
Thermoscope. — See  page  205. 
Thermostabile. — See  page  204. 
Thermo -tension. — Subjecting  red  hot  metal  to  high  tensile  stress 

which  is  maintained  during  cooling. 
Thicken. — To  expand  the  end  of  a  tube  which  is  to  be  threaded,  by 

an  amount  equal  to  the  depth  of  the  thread. 
Thickness.— (i)  Of  plates:  gage;  (2)  of  molten  slags,  etc.;  the  degree 

of  viscosity  or  fluidity. 
Thiel  Process. — See  page  388. 
Thin  Lined  Blast  Furnace. — See  page  27. 
Thiosulphate  Process. — See  page  96. 
Third  Order  Cells.— See  page  121. 
Thomas  Converter.— See  page  24. 

Thomas  or  Thomas-Gilchrist  Pig  Iron.— See  pages  343  and  346. 
Thomas-Gilchrist  Process.— See  page  15. 
Thomas  (G.  C.)  Process.— See  page  73. 
Thomas  (J.  W.)  Process.— See  page  319. 
Thomas  (S.  G.)  Process.— See  page  15. 
Thompson  Process.— See  page  118. 
Thomson  Effect.— See  page  209. 
Thomson  Process.— See  page  503. 
Thorn. — See  page  128. 
Three-high  Mill. — See  page  408. 
Three-pass  Stove. — See  page  34. 
Threw  Pyrometer.— See  page  210. 
Throat.— Of  a  blast  furnace:  see  page  27. 
Thurston's  Formulae.— For  tensile  strength:  see  page  339. 
Thundergust  Forge  (obs.).— An  irreverent  term  formerly  applied 

to  forges  blown  with  a  trompe. 
Thwing  Pyrometer. — See  page  207. 


486  TIEMANN'S  FORMULA—  TON 

Tiemann's  Formula.  —  For  quality:  see  page  341. 

Tilt  Hammer.  —  See  Hammer. 

Tilt  (Tilted)  Steel.—  Steel  hammered  with  a  tilt  hammer;  the  term  is 
now  restricted  to  blister  steel  which  has  been  hammered. 

Tilter.  —  See  page  411. 

Tilting  Converter.  —  See  page  17. 

Tilting  Furnace.  —  See  page  312. 

Tilting  Table.  —  See  page  408. 

Time.  —  Influence  of  on  strain  beyond  the  elastic  limit:  see  page  472. 

Timp.  —  See  page  32. 

Tin.—  Sn;  at.  wt,  119;  melt,  pt,  228°  C.  (442°  F.);  sp.  gr.,  crystal- 
line, 7.2,  amorphous,  5.8.  It  is  not  found  in  the  free  state. 
When  pure  it  is  a  white,  soft,  ductile  metal.  It  is  not  readily 
oxidized  at  ordinary  temperatures  and,  for  this  reason,  either 
alone  or  alloyed  with  lead,  is  used  for  coating  sheets  (see  pages 
429,  432).  It  combines  with  iron  in  all  proportions,  but  these 
alloys  are  not  of  importance  (see  page  453),  and  ordinarily  it 
occurs  in  steel  only  as  an  impurity. 

Tin  Bar.  —  See  page  429. 

Tin  Mill.—  See  page  430. 

Tin  (Tinned)  Plate;  Sheet.—  (i)  General:  see  page  429;  (2)  manu- 
facture of:  see  page  431. 

Tin  Plate  Bar.  —  See  page  429. 

Tin  Plating.  —  See  page  371. 
Pot.  — 


Tin  Pot;  Tinning  Pot.  —  See  page  431. 

Tin  Steels.  —  See  page  453. 

Tinman's  Pot;  Wire.  —  See  page  432. 

Tinting.  —  Heat  tinting:  see  page  288. 

Tintometer.  —  An  instrument  for  matching  colors,  e.g.,  in  colori- 
metric  determinations. 

Tipping  Converter.  —  See  page  17. 

Tipping  Furnace.  —  See  page  312. 

Titanate  Ore;  Titanic  Iron  Ore.  —  See  page  245. 

Titanium.—  Ti;  at.  wt.,  48.1;  melt,  pt.,  3000°  C.  (5432°  F.);  sp.  gr., 
3.54.  It  is  never  found  uncombined.  The  pure  metal  is  very 
hard  to  produce  on  account  of  its  great  affinity  for  oxygen  and 
nitrogen,  and  is  merely  a  chemical  curiosity.  It  is  obtained  as  an 
alloy  with  iron,  called  ferro-titanium  (seepage  355),  and  is  used 
to  a  certain  extent  as  an  addition  to  steel;  it  alloys  with  iron  in  all 
proportions. 

Titanium  Steels;  Titanium-treated  Steels.  —  See  page  453. 

Ton.  —  Owing  to  the  different  kinds  of  ton  it  is  always  necessary  to 
specify  which  one  is  intended,  and  it  is  well  to  give  the  equivalent 
in  pounds  avoirdupois  as  well  as  the  name.  The  names  and 
values  are  as  follows:  short  or  net  ton,  2000  pounds;  long  or  gross 
ton,  2  240  pounds  (this  is  the  British  standard,  and  is  always  meant 
when  "ton"  is  referred  to  in  British  publications);  a  special  long 
ton  of  2268  pounds,  sometimes  used  for  sand  cast  pig  iron,  \Y±% 
above  the  ordinary  long  ton  being  added  to  represent  approxi- 
mately the  adhering  sand;  double  gross  ton  (obs.),  2464  pounds,  a 
weight  10%  above  that  of  the  ordinary  long  ton;  metric  ton, 
1000  Kg.,  equivalent  to  2205  pounds,  nearly. 


TONNAGE— TRANSVERSE  DEFORMATION        487 

Tonnage  (Eng.). — See  page  472. 

Tool  Steel.— See  page  445. 

Tool  Temper.— See  Temper. 

Top. — (i)  Of  a  blast  furnace:  see  page  27;  (2)  of  an  ingot  or  piece: 

seepage  115. 

Top  Casting. — See  page  57. 
Top  Cut;  Discard.— See  Discard. 

Top  Heating;  Insulation;  Lag. — Of  ingots:  see  page  59. 
Top  Pouring. — See  pages  57  and  299. 
Top  Pouring  Ladle. — See  Ladle. 
Top  Replenishment. — See  page  59. 
Torpedo. — In  blast  furnace  practice:  see  page  35. 
Terrified. — See  page  73. 
Torsiometer. — See  page  477. 
Torsion. — See  page  330. 
Torsion  Test. — See  page  477. 
Torsional  Resilience. — See  page  331. 
Torsional  Strength. — See  page  330. 
Total  Carbon. — See  Carbon. 
Total  Cementation. — See  page  67. 
Total  Cementite. — See  page  273. 
Total  Ferrite. — See  page  272. 
Total  Heat.— See  page  202. 
Tough  Fracture. — See  page  178. 
Tough  Hardening. — See  page  232. 
Tough  Hardness. — See  page  452. 
Toughened  Cast  Iron. — See  Semi-steel. 
Toughening. — See  pages  230  and  232. 
Toughness. — See  pages  331  and  481. 
Tourangin  Process. — See  page  147. 
Track  Scales. — Heavy  scales  for  weighing  railroad  cars. 
Traction  Test.— See  page  469. 
Train. — Of  rolls:  see  pages  406  and  409. 
Transcarburization. — See  Carbon. 
Transcrystalline  Deformation. — See  page  282. 
Transcrystalline  Fracture. — See  page  178. 
Transcrystalline  Rupture. — See  page  282. 
Transfer  Caliper. — See  page  187. 
Transfer  Process. — See  page  21. 
Transference. — See  page  81. 
Transference  of  Heat. — Law  of:  see  page  221. 
Transformation;  Curve. — See  pages  81  and  326. 
Transformation  Point. — See  page  264. 
Transformation  Strains. — See  page  332. 
Transfusion. — Repouring:  see  page  21. 
Transition. — See  pages  81  and  271. 
Transition  Point. — See  page  264. 
Translation. — See  page  81. 
Translation  Banding. — See  page  127. 
Transmutation.— See  page  81. 
Transpiration  Pyrometer. — See  page  210. 
Transverse  Deformation.— See  page  337. 


488  .       TRANSVERSE  ROLLING— TRUE  FUSION 

Transverse  Rolling. — See  page  414. 

Transverse  Rupture. — See  page  336. 

Transverse  Seam. — See  Seam. 

Transverse  Strain. — See  page  337. 

Transverse  Strength. — See  page  330. 

Transverse  Test. — See  page  477. 

Transverse  Test  Piece. — See  page  469. 

Treading;  Treading  Floor.— In  the  manufacture  of  crucibles:  see 
page  ii2. 

Treatment  Crack. — See  page  222. 

Treatment  for  Grain  Size  and  Carbon. — See  page  218. 

Trebles. — Of  sheets:  see  page  433. 

Tree-like  Crystals. — See  page  122. 

Tressider  Process.— (i)  Armor  plate:  see  page  9;  (2)  heat  treat- 
ment: see  page  230. 

Triad. — (i)  In  chemistry:  see  page  86;  (2)  in  meteorites:  see  page 
291. 

Trial  Bar. — See  page  70. 

Triatomic. — See  page  87. 

Triaxial  Diagram. — See  Curve. 

Tribasic. — See  page  87. 

Triblet  (Eng.). — (i)  A  smith's  tool,  being  a  round  rod,  slightly 
tapered,  which  is  used  as  a  mandrel  around  which  rings  and  nuts 
are  finished  upon  the  anvil;  (2)  the  steel  core  upon  which  tubes 
are  drawn  to  produce  a  smooth  interior  surface  of  uniform 
diameter  (Horner). 

Trick,  Davis,  Daniel,  and  Phillips  Process.— See  page  380. 

Triclinic  System. — Of  crystallization:  see  page  120. 

Triclinohedral  System. — Of  crystallization:  see  page  120. 

Trimetric  System. — Of  crystallization:  see  page  120. 

Trimorphism. — See  page  121. 

Trio  Mill.— See  page  408. 

Trip  Hammer. — See  Hammer. 

Tripartite  Nature  of  Metals. — See  page  127. 

Triple-melting  Process. — See  page  75. 

Triplex  Process. — Sometimes  applied  to  a  process  involving  refin- 
ing in  three  stages  as  (a)  acid  Bessemer,  (6)  basic  open  hearth,  and 
(c)  basic  electric. 

Trivalent.— See  page  86. 

Troilite. — See  page  292. 

Trolley. — (i)  A  two-wheeled  truck  for  carrying  puddle  balls,  etc.; 
(2)  on  an  electric  crane,  the  part  carrying  the  hoisting  drum  which 
runs  back  and  forth. 

Troostite.— See  page  276. 

Troostp-Sorbite. — See  page  277. 

Troostitic  Martensite. — See  page  276. 

Tropenas  Converter;  Process. — See  page  24. 

Trosca  Process. — See  page  147. 

Trough  (Eng.). — Same  as  pot  in  the  cementation  process,  q.v. 

True  Calorie. — See  page  199. 

True  Elastic  Limit. — See  page  470. 

True  Fusion. — See  page  201. 


TRUE  PEARLITE— TUBES  489 

True  Pearlite. — See  page  273. 

True  Stress. — See  page  332. 

True  Welding. — See  page  501. 

Trunnel  Head. — See  page  95. 

Tschernoff's  Point. — See  page  265. 

Tschernoff's  Process. — See  page  233. 

Tuaran  (obs.). — Tuyere. 

Tub  (obs.).— Ladle. 

Tubes;  Tubing. — Tubes  or  pipes  are  long  hollow  metallic  cylin- 
ders. The  technical  distinction  between  the  two  is  that  tubes 
are  rated  according  to  the  outside,  and  pipes  according  to  the 
inside,  diameter  but,  in  general,  the  two  terms  are  used  inter- 
changeably. Cast  iron  pipe  is  necessarily  cast  in  molds,  the 
center  being  cored  out.  Welded  and  riveted  pipes  are  made 
from  plates  of  steel  or  wrought  iron  called  skelp  which  are  rolled 
up  longitudinally  into  shape  and  the  edges  welded  or  riveted 
together.  Close-jointed  skelp  is  the  name  sometimes  given  to  a 
tube  in  which  the  edges  of  the  skelp  are  brought  close  together, 
but  are  not  fastened.  If  the  skelp  is  bent  into  form  spirally, 
depending  upon  the  method  of  fastening  the  edges,  it  is  known  as 
spirally  welded  or  spirally  riveted  pipe.  In  the  welding,  depend- 
ing upon  whether  the  edges  simply  come  together,  or  overlap, 
butt  welded  or  lap  welded  pipe  is  produced,  the  former  being 
generally  restricted  to  sizes  up  to  about  3"  in  diameter,  while  the 
latter  method  is  used  for  sizes  up  to  36".  The  line  of  the  weld  is 
frequently  called  the  seam. 

Butt  Welding.— The  process  of  butt  welding  consists  in  draw- 
ing the  highly  heated  skelp  through  a  die  or  bell  having 
an  opening  of  the  exact  size  of  the  outside  of  the  pipe,  which 
serves  to  bend  the  skelp  into  form  and  at  the  same  time  pro- 
duce the  pressure  necessary  for  effecting  the  weld.  In  modern 
practice  tongs  are  thrust  through  the  bell  and  grip  the  end  of 
the  skelp  which  has  previously  been  cut  to  a  tapered  point, 
the  other  end  of  the  tongs  being  attached  to  a  buggy  or  car- 
riage moved  forward  by  an  endless  chain.  The  bell  is  kept 
in  position  by  resting  against  a  stop.  In  the  old  method,  known 
as  tag  butt  welding,  in  place  of  the  tongs,  a  rod  was  welded 
directly  to  the  end  of  the  skelp,  being  subsequently  cut  off. 
A  falling  seam  is  a  depression  on  the  top  (outside)  of  the  weld  due 
to  scant  width  of  skelp;  a  deep  seam  is  somewhat  similar,  but  the 
depression  occurs  on  both  sides,  due  to  round  edges  on  the  skelp. 
Lap  Welding. — In  this  method  the  edges  of  the  skelp  are 
usually  slightly  beveled  or  tapered  (scarfed)  so  when  they 
overlap  there  will  not  be  too  great  an  excess  of  metal.  The 
skelp  in  this  case  is  always  bent  (hot)  to  form  in  a  separate 
operation  called  piping  (rarely  skelping).  Formerly  a  machine 
called  a  skelper  (from  which  the  word  skelp  is  derived)  or 
crocodile  was  employed,  consisting  of  a  semi-circular  trough 
on  which  the  skelp  was  laid,  a  round-nosed  plunger  forcing  it 
down.  It  was  then  removed  and  bent  further  into  a  circle. 
In  modern  practice  this  bending  is  done  in  a  set  of  three  bending 
rolls,  one  roll  being  placed  between  and  slightly  above  two  other 


490  TUBES 

rolls,  the  height  depending  upon  the  diameter  of  the  pipe.  In 
welding,  as  one  edge  of  the  skelp  is  on  top  of  the  other,  two 
rolls,  with  grooves  corresponding  to  the  exact  diameter  of  the 
pipe,  are  provided  for  supplying  the  necessary  pressure  which 
is  resisted  on  the  inside  of  the  pipe  by  a  mandrel  or  ball  having 
the  exact  diameter  of  the  inside  of  the  pipe,  and  held  in  place 
by  a  rod.  Where  the  ball  is  on  the  same  side  as  that  on  which 
the  pipe  enters  the  rolls,  the  operation  is  called  rolling  off;  if 
on  the  opposite  side,  rolling  on.  For  certain  purposes,  such  as 
boiler  tubes,  where  the  pipe  is  to  be  subjected  to  high  internal 
pressure,  the  whole  welding  operation  may  be  repeated,  the 
product  then  being  known  as  rewelded  pipe. 

After  welding,  both  butt  and  lap  welded  pipes  are  made  per- 
fectly round  by  passing  them  through  a  set  of  grooved  rolls, 
called  -sizing  rolls,  and  are  then  made  straight  by  passing  them 
through  the  straightening  rolls.  Tubes  which  are  straightened 
hot,  particularly  the  larger  sizes,  are  usually  put  through  cross 
rolls,  consisting  of  two  concave  rolls,  one  above  the  other,  and 
with  their  axes  set  at  an  acute  angle.  They  both  revolve  in 
the  same  direction,  which  causes  the  pipe  to  rotate  very  rapidly 
and  at  the  same  time  to  move  slowly  forward.  The  pipes  are 
then  cooled  on  some  form  of  cooling  bed,  cut  to  length,  etc. 
Another  form  of  straightening  machine  is  like  an  ordinary  gag 
press.  There  are  two  grooved  rollers  over  which  the  pipe  is 
run,  and  a  third  roller,  spaced  between  -the  other  two,  is  brought 
down  on  the  top  of  the  pipe  to  take  out  any  curvature.  A 
third  type  has  one  set  of  vertical  and  one  set  of  horizontal 
grooved  rollers,  of  about  six  each,  and  spaced  the  right  distance 
apart  for  the  given  diameter  of  pipe. 

Rifled  pipe  is  a  kind  recently  introduced  for  use  in  the  trans- 
mission of  oil.  It  has  spiral  laminations  rolled  in  it  which 
give  the  oil  a  whirling  motion,  a  certain  amount  of  water  which 
is  present  being  thereby  thrown  to  the  periphery  and  lessening 
the  friction.  Perrins  process  for  making  welded  tubes  consists 
in  first  rolling  puddled  bars  into  a  trough  section,  which  are 
then  piled  together  in  tubular  form,  with  the  longitudinal  abut- 
ting edges  placed  so  as  to  break  the  joint,  and  the  pile  is  then 
rolled  into  a  tube. 

Seamless  or  weldless  tubes  are  always  manufactured  of 
steel  on  account  of  the  great  homogeneity  necessary.  They 
are  generally  made  from  solid  round  billets  which  are  heated 
and  then  pierced  by  a  mandrel  (no  longer  drilled  on  account  of 
the  cost),  after  which  they  are  rolled  over  mandrels  to  obtain 
the  proper  diameter  and  thickness  of  wall,  much  in  the  manner 
already  described  for  lap  welding,  except  that  a  number  of 
passes  are  necessary.  There  are  two  methods  of  piercing:  (a) 
in  the  Mannesmann  process  a  pair  of  special  conical  rolls  (pilger 
rolls),  both  of  which  revolve  in  the  same  direction,  rotate  the 
billet  very  rapidly  and  at  the  same  time  drive  it  slowly  forward 
over  a  pointed  mandrel  situated  between  them.  The  action 
here  is  very  peculiar,  as  the  hole  is  not  produced  by  the  mandrel 
but  by  the  rolls  which,  by  exerting  a  pressure  on  the  billet  at  two 


TUBES 


491 


diametrically  opposed  points,  continuously  changing,  cause  a 
central  cavity  to  open  up,  the  mandrel  serving  simply  to  open  up 
the  end  and  smooth  the  interior.  This  phenomenon  is  known  as 
internal  rupture  and  may  also  be  produced  by  hammering.  A 
different  style  of  rolls  to  effect  the  same  result  has  been  designed 


FIG.  64. — The  Mannesmann  process  for  rolling  weldless  steel  tubes. 

by  R.  C.  Stiefel.  (b)  In  the  Erhardt  process  a  round-nosed 
mandrel  is  forced  longitudinally  through  a  square  billet  enclosed 
in  circular  dies,  the  difference  in  cross-sectional  area  between  the 
two  giving  the  space  necessary,  for  the  metal  displaced  into  the 
wall  of  the  billet  by  the  mandrel.  Tubes  so  produced  may  be 
hot  or  cold  drawn  to  final  size,  the  principle  being  the  same  as  in 


FIG.  65. — The  Stiefel  process  for  rolling  weldless  steel  tubes. 

wire  drawing;  but  since  a  tube  is  hollow,  it  must  be  drawn  over  a 
mandrel  to  prevent  it  from  being  crushed.  In  cold  drawing 
the  tube  is  first  pickled  in  a  bath  of  dilute  sulphuric  acid,  heated 
by  steam,  to  remove  all  scale  which  if  left  would  spoil  the  surface 
and  scratch  the  dies.  It  is  then  rinsed  in  water  and  drawn 
without  further  treatment.  Tallow  and  sawdust,  or  some  other 


492  TUBERCULAR  CORROSION— TURGITE 

form  of  lubricant,  are  used  both  outside  and  inside.  The  tube 
must  be  annealed  and  pickled  after  each  drawing.  For  ordinary 
purposes  two  drawings  are  usually  sufficient,  but  for  very  thin 
walls  seven  or  eight  may  be  required.  With  cold  drawing  the 
operation  is  rarely  commenced  before  the  walls  have  been  reduced 
to  %";  with  hot  drawing  the  thickness  of  the  walls  is  not  generally 
carried  below  %" '.  Seamless  tubes  made  from  billets  range  in  size 
from  about  2"  up  to  5/^"  outside  diameter.  Above  this,  to  about 
20",  they  are  manufactured  from  plates,  and,  as  a  rule,  in  shorter 
lengths.  By  this  process  a  plate,  sheared  into  a  circle,  is  heated 
and  cupped,  i.e.,  forced  by  a  mandrel  through  a  circular  die,  and 
then  after  reheating,  is  similarly  forced  by  another  mandrel 
through  a  succession  of  dies  held  in  position  in  a  heavy  trough- 
like  machine  until  the  thickneess  of  the  wall  has  been  reduced 
considerably.  Further  reduction  is  effected  by  drawing  in  the 
manner  already  described  for  seamless  tubes  made  from  billets. 
Cylinders  for  gases,  etc.,  to  withstand  great  pressure,  are  made 
by  this  method,  the  open  end  being  swaged  down  and  fitted 
with  a  suitable  cock. 

Robertson's  process  is  a  method  for  producing  seamless 
tubes  (somewhat  similar  to  Erhardt's)  by  piercing  longitudi- 
nally a  blank  fitting  a  die,  a  pressure  plate  being  held  against 
the  far  end  to  prevent  the  mandrel  from  tearing  the  piece. 
The  further  rolling  is  as  usual. 

The  Kellogg  process  is  also  for  producing  seamless  tubes, 
and  consists  in  casting  an  ingot  with  a  hollow  center.  This 
is  put  over  a  mandrel  and  rolled  out  until  the  wall  is  of  the 
desired  thickness. 

Finished  tubes  are  tested  principally  with  hydraulic  pressure. 
Those  which  fail  are  known  as  blowers  or  leakers ;  sand  blowers 
(lap  welded)  are  those  which  have  dirt  in  the  weld;  iron  blowers 
(lap  welded),  those  which  have  longitudinal  cracks. 

Tubercular  Corrosion. — See  page  106. 

Tue  Iron  (obs.). — Tuyere. 

Tuiron  (obs.). — Tuyere. 

Tumbler;  Tumbling  Barrel. — See  page  58. 

Tungstate  Ore. — See  page  245. 

Tungsten.— W;  at.  wt.;  184;  melt,  pt,  3267°  C.  ±30°  (5913°  F.  ± 
54°);  sp.  gr.,  18.77.  It  is  always  found  combined.  The  pure 
metal  is  white  but  is  not  employed  in  that  condition.  It  is 
obtained  as  an  alloy  with  iron,  termed  ferro-tungsten  (see 
page  355),  and  is  used  in  the  manufacture  of  certain  special 
steels  (see  page  450) ;  it  alloys  with  iron  in  all  proportions. 

Tungsten-Chrome  Steels. — See  page  450. 

Tungsten  Hardenite. — See  page  275. 

Tungsten  Steels. — See  page  450. 

Tunnel  Head. — See  page  34. 

Tunnel  Kiln  Process. — See  page  44. 

Tup. — (i)  Of  a  hammer:  see  page  195;  (2)  of  a  drop  test  machine: 
see  page  481. 

Turbo  Blowers. — See  Blowing  Engines. 

Turgite. — See  page  244. 


TURK  PROCESS— TYROL  PROCESS  493 

Turk  Process. — See  page  420. 

Turn. — A  working  period,  also  the  men  composing  one  shift.     A 

plant  running  on  single  turn  works  for  ten  to  twelve  hours  per 

day;  double  turn;  two  shifts  of  twelve  hours  each;  triple  turn: 

three  shifts  of  eight  hours  each. 
Turn  Down. — (i)  Of  a  converter:  see  page  17;  (2)  in  rolling:  see 

page  412. 

Turn  Up. — Of  a  converter:  see  page  20. 
Turner  Method. — To  determine  hardness:  see  page  480. 
Turner  Process. — See  page  6r. 
Turner  Sclerometer. — See  page  480. 
Turnover. — Repeater,  in  rolling:  see  page  416. 
Tuyere;  Tuyere  Arch;  Tuyere  Arch  Cooler;  Tuyere  Block. — See 

page  31. 

Tuyere  Box;  Brick. — See  page  17. 
Tuyere  of  Combustion. — See  page  24. 
Tuyere  Plate. — See  page  135. 
Tweer  (obs.).— Tuyere. 
Twere  (obs.).— Tuyere. 
Twin;  Axis;  Crystal. — See  page  124. 
Twinning;  Axis;  Law. — See  page  124. 
Twinning  Plane. — See  page  123. 
Twisted  Guide. — See  page  41 2. 
Two-high  Mill.— See  page  408. 
Two-pass  Stove. — See  page  34. 
Twyer;  Twyere  (Eng.).— Tuyere. 
Twynam  Process.— (i)  Direct  process:  see  page  147;  (2)  for  steel: 

see  page  319. 
Tying.— See  page  300. 
Tymp;  Plate;  Stone. — See  page  32. 
Type.— Of  steel:  see  page  455. 
Tyrol  Process. — See  page  79. 


u 

U.  —  Chemical  symbol  for  uranium,  q.v. 

U.  S.  Gage.  —  (i)  Standard  for  sheet  and  plate  iron,  and  steel:  see 


page  1  88;  (2)  for  steel  wire:  see  page  188. 
chati 


Uchatius  Process.  —  See  page  113. 

Uehling  Process.  —  See  page  388. 

Uhling-Steinbart  Pyrometer.  —  See  page  209. 

Ultimate  Analysis.  —  See  page  82. 

Ultimate  Shortening.  —  See  page  336. 

Ultimate  Strength;  Stress.  —  See  page  335. 

Ultimate  Structural  Composition.  —  See  page  337. 

Ultramicroscopic.  —  See  page  284. 

Uncombined  Carbon.  —  See  Carbon. 

Underburdened.  —  Of  a  blast  furnace:  see  page  34. 

Undercooling.  —  See  page  268. 

Undercut.  —  Of  patterns:  see  page  296. 

Understrained  Ferrite.  —  See  page  216. 

Unequal  Cooling.  —  See  page  222. 

Unequal  Heating.  —  See  page  223. 

Uneven  Fracture.  —  See  page  179. 

Unicellular  Structure.  —  See  page  126. 

Uniform  Load.  —  See  page  468. 

Uniformity.  —  In  heat  treatment:  see  page  212. 

Unit  Crystal.  —  See  page  122. 

Unit  Stress.—  See  page  333. 

United  States  Gage.  —  (i)  Standard  for  sheet  and  plate  iron  and 

steel:  see  page  188;  (2)  for  steel  wire:  see  page  188. 
Univalent.  —  See  page  86. 
Universal  Mill.  —  See  pages  408  and  413. 
Unsatisfied.  —  See  Satisfied. 
Unsaturated  Steel.—  See  page  273. 
Unsegregated  Pearlite.  —  See  page  276. 
Unstable  Crystallographic  Equilibrium.  —  See  page  217. 
Unstable  Equilibrium.  —  See  page  326. 
Unstressed.—  See  page  332. 
Uphead.—  See  Upset. 
Upset.  —  To  enlarge  the  cross-section  of  a  piece  of  metal  at  one  end 

by  striking  or  pressing  that  end;  to  uphead. 
Upper  Freezing  Point.  —  See  page  267. 
Uptake.  —  (i)  In  an  open  hearth  furnace:  see  page  310;  (2)  in  a  gas 

producer,  the  passage  connecting  the  combustion  chamber  with 

the  gas  main. 

Upton's  Equilibrium  Diagram.  —  See  page  272. 
Uranium.-*!!;  at.  wt.,  138.5;  melt,  pt.,  800°  C.  (1472°  F.);  sp.  gr., 

18.7.    It  is  not  found  free  in  nature.    When  pure  it  is  a  heavy 

494 


URANIUM  STEELS— UTRICULAR  495 

white  metal.  It  has  recently  had  some  application  as  an  addi- 
tion to  steel  (see  Special  Steels,  p.  453). 

Uranium  Steels. — See  page  453. 

Uses  (Eng.)- — A  rough  block  (reduced  from  an  ingot)  to  be  made 
into  small  forgings,  or  ready  to  be  machined  to  final  form. 

Utricular. — See  page  120. 


V. — (i^Volumej  (2)  chemical  symbol  for  vanadium,  q.v.;  (3)  point 
of  Brinell:  see  page  265. 

V-weld. — See  page  502. 

Vacuum  Casting. — See  page  62. 

Vacuum  Gases  (Howe).— Those  obtained  on  heating  metal  in 
vacuo. 

Vacuum  Tuyere. — See  page  32. 

Valence;  Valency. — See  page  86. 

Valence  Formula. — See  page  86. 

Valency  Theory. — Of  passivity:  see  page  364. 

Van  Aller  Process. — See  page  372. 

Van  der  Waal's  Formula.— See  Gas. 

Van  Riet  Process. — See  page  60. 

Vanadium.— V;  at.  wt.,  51.2;  melt,  pt,  1680°  C.  (3056°  F.);  sp. 
gr.,  6.025.  It  is  a  comparatively  rare  element  and  is  always 
found  combined.  When  pure  it  is  a  white  metal  having  a 
great  affinity  for  oxygen  and  nitrogen.  Owing  to  the  discovery 
of  large  mineral  deposits,  it  has  recently  come  into  considerable 
use  in  the  manufacture  of  special  steels  (see  page  452);  it  alloys 
with  iron  in  all  proportions,  and  is  obtained  commercially  as 
ferro-vanadium  (see  page  356).  The  element  was  first  isolated 
in  1803  by  Del  Rio  who  called  it  eurythronium ;  its  present  name 
was  given  in  1830  by  Sefstrom. 

Vanadium  Hardenite. — See  page  275. 

Vanadium  Steels. — See  page  452. 

Vanado-Fenite. — See  page  272. 

Vapor. — See  page  202. 

Vapor  Pressure  Pyrometer. — See  page  210. 

Vapor  Pyrometer. — See  page  209. 

Vaporization. — See  page  202. 

Variable  Pressure  Thermometer. — See  page  205. 

Variable  Volume  Thermometer. — See  page  205. 

Variability,  Degree  of. — See  page  327. 

Vectorial  Movement. — See  page  281. 

Vehicle. — Of  a  paint:  see  page  365. 

Vein. — See  page  58. 

Vein  Stuff  (Eng.). — The  gangue  or  matrix  of  an  ore. 

Velocity  of  Cementation. — See  page  67. 

Velocity  of  Transformation. — See  page  265. 

Vent  Hole;  Wire. — See  page  298. 

Ventilation;  Venting. — See  page  298. 

Vertical  Heating  Furnace. — See  page  184. 

Vertical  Illumination. — See  page  285. 

496 


VERTICAL  REGENERATORS— VUG  497 

Vertical  Regenerators. — See  page  312. 

Vertical  Shear. — See  page  336. 

Vertical  Testing  Machine. — See  page  469. 

Vessel. — A  Bessemer  converter:  see  page  15. 

Vessel  Patching.— See  page  17. 

Vibration. — See  page  333. 

Vibrator  Machine. — See  page  301. 

Vibratory  Brittleness. — See  Brittleness. 

Vibratory  Test. — See  page  482. 

Vical's  Experiment. — See  page  334. 

Vickers  Process. — See  page  118. 

Villon  Process. — See  page  374. 

Violent  Aeration. — See  page  107. 

Violent  Cement. — See  page  67. 

Violle's  Actinometer. — See  page  207. 

Violle  Calorimetric  Pyrometer. — See  page  207. 

Viscous  Materials. — See  page  331. 

Visible  Color. — See  page  210. 

Visual  Analysis. — See  page  284. 

Visual  Microscopy. — See  page  284. 

Vitreous  Amorphous  Phase. — See  page  281. 

Vitreous  Fracture. — See  page  179. 

Vitreous  Fusion. — See  page  201. 

Vitricarbo. — See  page  398. 

Vitriform  Fracture. — See  page  179. 

Vitriol. — Oil  of  vitriol:  commercial  sulphuric  acid. 

Vivianite. — See  page  244. 

Void. — Pipe:  see  page  53. 

Volatile  Matter.— See  Fuel. 

Voltaic  Contact. — That  between  unlike  metals,  causing  an  electro- 
lytic action. 

Voltex  Process. — See  page  503. 

Volume  Force. — See  page  331. 

Volume  Increase. — From  quenching:  see  page  225. 

Volumenometric  Thermometer. — :See  page  207. 

Volumetric  Modulus  of  Elasticity. — See  page  335. 

Volumetric  Thermometer. — See  page  207. 

Vom  Baur  Furnace. — See  page  165. 

Von  Maltitz  Process.— See  page  388. 

Von  Nawrocki  Process. — See  page  64. 

Vug;  Vug  Crystals. — A  cavity  in  a  casting,  etc.,  and  crystals  found 
in  such  cavities. 


32 


w 

W. — (i)  Chemical  symbol  for  tungsten,  q.v.;  (2)  point  of  Brinell: 

see  page  265. 

W  Structure. — See  page  291. 
Wabbler. — See  page  407. 
Wagner  Process. — See  page  371. 
Waidner  and  Burgess  Pyrometer. — See  page  208. 
Walker  Process. — See  page  371. 
Wall. — One  of  the  sides  of  a  furnace;  in  a  circular  furnace,  the 

vertical  portion. 

Wall  (Arthur)  Process. — See  page  73. 
Walled  Cell. — See  page  121. 
Wallerant's  Process. — See  page  232. 
Walloon  Processes. — See  page  75. 
Walrand  Converter. — See  page  24. 
Walrand-Delattre  Converter. — See  page  24. 
Walrand  and  Delattre  Process. — See  page  23. 
Walrand  and  Legenisel  Process. — See  page  23. 
Walrand  Process. — See  pages  23  and  388. 
Wanner  Optical  Pyrometer. — See  page  207. 
Ward  Process.— See  page  370. 
Warm  Blast.— See  Blast. 
Warm  Blast  Charcoal  Iron.— See  page  350. 
Warner  Process. — (i)   Basic  Bessemer  process:  see  page  23;  (2) 

for  desulphurizing:  see  page  388. 
Warped. — See  page  56. 
Wash. — (i)  Wearing  of  molds:  seepage  57;  (2)  coating  for  molds: 

see  page  298. 
Wash  Heat. — A  heat  which  causes  the  scale  on  the  surface  of  a 

piece  of  iron  or  steel  to  melt  and  run  off;  also  called  a  cinder  heat: 

(2)  used  in  the  sense  of  reheating  merely  the  outside  of  a  piece* 

where  it  has  become  slightly  chilled  from  rolling  or  forging,  the 

interior  being  still  sufficiently  hot;  (3)   in  open  hearth  practice; 

see  page  313. 

Wash  Metal.— See  page  384. 
Wash  Out  Heat.— See  page  313. 
Wash  Pot.— See  page  298. 
Wash  Up.— See  page  298. 
Wash-welding  Temperature.— See  page  116. 
Washburn  and  Moen  Gage.— See  page  188. 
Washed  Metal;  Pig. — See  pages  346  and  384. 
Washer.— See  Ore. 
Washing.— (i)  Of  gas:  see  page  33;  (2)  see  Wash  Heat;  (3)  of  ore, 

q.v. 

498 


WASHING  PROCESS— WATER  GAS  499 

Washing  Process. — Pig  washing  process:  see  page  383. 

Wassell  Process. — See  page  420. 

Wassereisen  (obs.). — See  Hydrosiderum. 

Waste  Gases. — See  page  202. 

Waste-heat  Oven.— See  page  96. 

Waste  Liquor. — See  Pickling. 

Waste  Wax  Process. — See  page  301. 

Waster. — An  article  rejected  on  account  of  imperfections  developed 
in  the  course  of  manufacture;  scrap.  This  term  is  applied  more 
especially  to  defective  sheets  and  tin  plates. 

Water. — H2O;  it  occurs  in  practically  every  non-metallic  sub- 
stance unless  it  is  specially  removed  by  drying  (desiccation), 
and  is  then  often  termed  moisture.  It  may,  so  to  speak,  be 
simply  mixed,  so  that  heating  to  a  temperature  slightly  above 
its  boiling  point  will  expel  it:  in  this  case  it  is  called  hygroscopic 
moisture  (rarely  hygrometric  water)  or  mechanically  combined 
water.  The  action  whereby  a  solid  substance  parts  with  its 
moisture  upon  exposure  to  ordinary  air  is  termed  efflorescence 
(the  substance  is  said  to  effloresce);  where  additional  moisture 
is  taken  up  it  is  known  as  deliquescence  (the  substance  is  said 
to  deliquesce).  Where  the  water  is  more  closely  bound  and 
appears  to  enter  into  a  weak  chemical  combination,  so  that  a 
temperature  considerably  above  its  boiling  point  is  necessary 
to  expel  it,  it  is  termed  combined  water,  water  of  crystallization, 
or  water  of  combination;  an  example  of  this  is  copper  sulphate 
which  is  generally  seen  in  the  form  of  beautiful  blue  crystals 
having  the  formula  CuSO4-7H2O;  upon  drying  at  a  fairly  high 
temperature,  the  water  is  driven  off  and  a  white  powder  results. 

Water  Annealing.— See  page  231. 

Water  Breast.— See  page  31. 

Water  Coating. — See  page  507. 

Water  of  Combination.— See  Water. 

Water  of  Crystallization.— See  Water. 

Water  Cooled;  Cooling. — See  page  227. 

Water  Core. — See  page  299. 

Water  Crack.— See  Crack. 

Water  Dipping.— See  page  227. 

Water  Equivalent.— See  page  201. 

Water  Finish. — The  finish  or  appearance  of  machined  metal  ob- 
tained when  a  small  stream  of  water  trickles  upon  the  cutting 
tool. 

Water  Gas. — A  fuel  gas  produced  by  the  decomposition  of  steam 
with  incandescent  carbon.  The  fuel  is  maintained  in  a  thick 
bed  in  an  apparatus  called  a  water  gas  producer  (rarely  simply 
gas  producer),  and  the  process  consists  of  two  periods;  during 
the  first  period  (sometimes  called  blowing  up  or  blowing  hot) 
air  is  blown  through  the  fuel  until  it  becomes  incandescent, 
the  gases  formed  being  allowed  to  escape;  in  the  second  period 
(steaming  or  blowing  cold)  the  air  is  turned  off  and  steam  is 
blown  through  the  fuel,  the  gas  so  formed  being  led  to  the  gas 
receiver:  this  is  kept  up  until  the  fuel  is  so  much  cooled  that 
the  reaction  becomes  very  imperfect.  The  theoretical  compo- 


500  WATER  HARDENING— WELDED  PIPE 

sition  of  the  gas  is  50%  each  of  hydrogen  and  carbon  monoxide. 
Ledebur  gives  the  following  as  the  usual  range  by  volume: 

Hydrogen ; 44.0  to  53.0% 

Carbon  monoxide 45 .  o  to  40 .  o 

Methane ,  4 .  o  to    o .  o 

Carbon  dioxide i .  5  to    6.0 

Nitrogen... 8.0  to    i.o 

Water  Hardening. — See  page  227. 

Water  Hardening  High  Speed  Tool  Steels.— See  page  448. 
Water  Helve. — See  Hammer. 

Water  Jacket. — A  metallic  casing  through  which  water  circulates  to 
keep  the  interior  of  a  furnace  wall  from  being  corroded  or  burned 


away,  i.e.,  to  keep  it  "cool." 
Water  Oil  Gas.— See  Oil  Gas. 


Water  Pot. — See  page  298. 

Water  Pyrometer. — See  page  207. 

Water  Quenching.— See  page  227. 

Water  Seal  Producer.— See  Producer.          \&?..  «r 

Water  Tempering.— See  page  227. 

Water  Toughening. — See  pages  227  and  445. 

Watery  Fusion. — See  page  201. 

Watson  (J.  J.W.)  Process. — See  page  73. 

Watts  Process.— See  page  166. 

Wave.— See  Flute. 

Weak.— Brittle,  q.v. 

Weak  Iron. — White,  brittle  pig  iron. 

Wearing  Tests.— See  page  480. 

Weathering. — Exposure  to  the  atmosphere;  used  in  the  case  of  ores 
which  are  exposed  for  a  considerable  period  (months  or  years) 
to  assist  in  their  disintegration  and  in  removing  or  oxidizing 
impurities. 

Webster's  Formula. — For  tensile  strength:  see  page  339. 

Wedging  Down. — Of  top-poured  iron  ingot  molds;  capped  with 
sand  and  an  iron  plate  held  in  place  by  a  wedge  driven  under  a 
bar  passing  through  rings  in  the  top  of  the  mold. 

Wedgwood's  Contraction  Pyroscope. — See  page  209. 

Weigelin  Process. — See  page  369. 

Weigh  Bar.— See  page  475. 

Weight  Percent.— See  page  83. 

Weiss  Process. — See  page  44. 

Weld. — See  page  501. 

Weld  Iron. — A  term  suggested  for  wrought  iron  but  seldom  used. 

Weld  Metal. — A  term  suggested  by  Von  Ehrenwerth  for  iron 
products  produced  in  a  pasty  (containing  slag)  condition. 

Weld  Steel. — Iron  containing  sufficient  carbon  to  be  capable 
of  hardening  greatly  by  sudden  cooling,  and  in  addition  slag 
bearing,  because  made  by  welding  together  pasty  particles  of 
metal  in  a  bath  of  slag,  as  in  puddling,  and  not  later  freed  from 
that  slag  by  melting.  The  term  is  rarely  used  (I.  A.  T.  M.). 

Welded  Joint.— See  page  501. 

Welded  Pipe.-— See  page  489. 


WELDING  501 

Welding. — (a)  Strictly  a  method  of  uniting  two  pieces  of  wrought 
iron  or  steel  by  heating  them  to  a  temperature,  moderately  close 
to  their  melting  point  (but  without  actual  fusion),  at  which  they 
become  pasty,  and  forcing  them  into  intimate  contact  whereby 
molecular  cohesion  takes  place,  producing  a  weld  or  welded  joint. 
(6)  In  recent  years  methods  are  included  which  employ  actual 
melting  either  of  a  substance  which  acts  as  a  solder  or  of  a  portion 
of  one  or  both  of  the  pieces  which  are  to  be  united.  Stead  de- 
scribes (a)  or  true  welding  as  "the  crystallizing  into  union  of  two 
metallic  surfaces  when  they  are  brought  together  under  suitable 
conditions.  That  such  is  the  case  is  proved  by  microscopic 
examination,  for  on  polishing  and  etching  sections  of  the  united 
metals,  the  crystals  along  the  junction  are  found  to  be  common  to 
each  of  the  original  pieces  of  metal.  In  perfect  welding  there  is 
no  visible  joint,  for  the  line  or  plane  of  junction  is  occupied  by 
crystals,  portions  of  which  belong  to  one  piece  of  metal  and 
portions  of  the  same  crystals  to  the  other.  When  the  boundaries 
of  the  crystals  are  coincident  with  the  juxtaposed  plane  surfaces 
it  is  evidence  of  non- welding,  which  is  equivalent  to  saying  that 
'unless  the  crystals  become  common  to  the  two  pieces  there  is  no 
welding'  "  (Stead's  Law  of  Welding). 

The  temperature  necessary  for  ordinary  welding  is  a  good  white 
heat  (welding  heat  or  temperature),  say  1250  to  1350°  C.  (2280  to 
2460°  F.)  for  soft  steel,  and  in  some  cases  slightly  higher  for 
wrought  iron.  As  this  makes  the  grain  very  coarse,  hammering 
or  some  other  form  of  work  is  usually  necessary  to  refine  it; 
annealing  or  some  form  of  heat  treatment  alone  i  may  in  some 
cases  be  sufficient  (see  Heat  Treatment,  page  231).  Hammered 
weld  is  the  term  sometimes  used  for  such  welds  particularly  to 
distinguish  them  from  those  (chiefly  electrical  or  thermit  welds) 
which  are  simply  pressed  together  at  a  high  temperature  and 
may,  in  consequence,  have  a  coarse  grain  from  not  having  been 
worked  down  to  a  low  temperature.  By  the  Komrn  method  of 
welding  the  union  of  the  two  pieces  is  produced  within  the  fire 
where  the  two  conically  pointed  ends  are  in  contact.  The  crust 
of  cinders  is  removed  by  blows  applied  to  the  butts  which  project 
from  the  hearth,  and  since  the  two  surfaces  which  are  thus  kept 
pure  cling  to  one  another  at  once  and  unite,  there  is  no  opportu- 
nity for  a  renewed  oxidation.  Rods  which  are  welded  in  this  way 
do  not  separate  under  alternating  torsional  bending  along  the 
faces  welded,  but  they  break  across  the  axis  of  the  rod,  just  like 
rods  which  have  not  been  welded  (Bermann).  At  the  moment  of 
welding  it  is  essential  to  have  the  surfaces  clean,  i.e.,  free  from 
scale  or  dirt,  to  remove  which  a  flux  is  commonly  used,  ordinarily 
sand  for  steel  and  borax  for  wrought  iron.  The  term  welding 
cinder  is  sometimes  employed  for  one  which  is  easily  fusible  and, 
while  protecting  the  surfaces  from  oxidation,  will  run  out  readily 
when  they  are  pressed  together.  It  has  been  recommended  to 
have  the  surfaces  convex  to  each  other  so  they  will  at  first  touch 
on  a  line  near  the  middle  and  the  liquid  slag  will  be  forced  out  as 
the  weld  is  formed  instead  of  being  inclosed  as  might  easily  be  the 
case  if  the  surfaces  were  concave.  The  flux  is  sometimes  formed 


502  WELDING 

into  a  thin  plate  (welding  plate)  which  is  placed  between  the  two 
surfaces,  and  in  this  case  is  frequently  of  a  special  composition. 
W.  B.  Middleton  dips  the  pieces  to  be  welded  into  a  solution  of 
sodium  silicate,  after  which  they  are  heated  and  welded  in  the 
usual  manner. 

The  strength  of  a  weld  (i.e.,  of  the  material  at  the  joint)  is 
almost  never  equal  to  that  of  the  original  section,  although  in 
some  cases,  particularly  with  wrought  iron,  it  may  approach  it 
very  closely.  Defective  welds  may  be  caused  by  (a)  heating  too 
high:  burning;  (b)  heating  too  low:  molecular  cohesion  not 
effected;  (c)  not  working  sufficiently  at  the  weld,  back  from  the 
weld,  or  both:  brittle;  (d)  surfaces  not  clean;  (e)  sulphur  too  high; 
(/")  carbon  too  high.  It  should  be  appreciated  that  one  of  these 
conditions  may  directly  affect  another;  for  example,  if  the  carbon 
is  higher  than  usual  the  temperature  cannot  be  so  high  without 
danger  of  burning,  but  if  too  low  good  cohesion  will  not  be  se- 


Lap  or  Scarf  Weld  Butt  or  Jump  Weld 


V 


V-Weld  V-Weld  with  Binder 


Split  Weld 
FIG.  66. — Types  of  weld. 

cured.  It  is  also  of  interest  that  experiments  with  relatively 
high  sulphur  steel  developed  the  fact  that  the  temperature  had 
to  be  lower  (or  shorter  time  of  heating  under  the  same  conditions) 
than  with  low  sulphur  stock;  the  welds  produced  in  this  way  were 
entirely  satisfactory.  There  are  a  number  of  types  of  weld 
which  are  sufficiently  explained  by  Fig.  66. 

V-welds  and  V-welds  with  binder  are  sometimes  called  respec- 
tively bird's-mouth  welds,  and  glut  welds.  Cross  welding, 
employed  in  the  manufacture  of  extra-long  lengths  of  tubes, 
consists  in  welding  two  pieces  of  skelp  together  at  the  ends  before 
bending  and  welding  the  edges.  The  line  of  the  weld  is  called  the 
joint  or  sometimes  the  shut  or,  particularly  in  the  case  of  welded 
tubes,  the  seam.  A  cold  shut  is  where  the  hammering  has  not 
been  carried  far  enough  to  obliterate  the  line  or  joint  between  the 


WELDING  503 

two  pieces:  the  weld  is  not  smooth  but  otherwise  may  be  all 
right. 

An  experiment  to  show  that  welding  may  occur  at  a  tempera- 
ture only  slightly  above  the  upper  critical  point  is  known  as 
Coffin's  weld  or  joint.  It  consists  in  taking  a  small  bar  of  tool 
steel,  breaking  it  to  obtain  a  fresh  fracture  (two  pieces  may  also  be 
machined  to  produce  clean  surfaces  fitting  accurately),  which 
are  then  fitted  together.  They  are  wrapped  in  platinum  foil 
to  prevent  oxidation,  and  are  heated  with  an  ordinary  Bunsen 
burner  (or  otherwise)  when  the  pieces  will  unite  more  or  less 
completely,  unassisted  by  any  hammering. 

In  ordinary  (or  "old-fashioned")  welding  the  pieces  are  gener- 
ally heated  in  a  coke  fire  or  in  some  form  of  regular  heating  fur- 
nace. An  oxy hydrogen  flame  (oxyhydrogen  welding)  is  some- 
times employed,  which  is  the  principle  of  Garut's  process,  and 
more  recently  considerable  application  has  been  made  of  an 
oxyacetylene  flame  (oxyacetylene  welding),  both  of  these 
methods  being  chiefly  applicable  to  small  or  thin  pieces  such  as 
sheets.  Owing  to  the  extremely  high  temperatures  produced 
such  welds  are  sometimes  referred  to  as  hot  flame  welds ;  the 
temperatures  are  so  high  that  frequently  (and  by  intention) 
actual  fusion  occurs.  Oxyhydrogen  and  oxyacetylene  cutting 
are  simply  a  further  application  of  this  possibility  by  melting 
away  the  metal  in  order  to  remove  portions  of  an  object;  with  a 
substance  containing  carbon  (any  form  of  wrought  iron,  cast  iron 
or  steel)  after  a.  point  of  incandescence  is  reached  it  is  sufficient 
to  shut  off  the  hydrogen  or  acetylene,  as  the  case  may  be,  and  the 
oxygen  under  heavy  pressure  will  burn  and  fuse  the  metal  in  the 
immediate  vicinity,  which  is  blown  away.  By  employing  a  fine 
jet  a  very  narrow  cut  may  be  effected. 

The  necessary  heat  may  also  be  supplied  electrically  (electric 
welding) :  (a)  with  an  arc  (arc  welding)  in  which  the  pieces  are 
heated  by  direct  contact  or  by  radiation;  (b)  by  the  resistance  of 
the  pieces  themselves  to  the  passage  of  the  current  (incandescent 
welding  or  resistance  welding);  and  (c)  by  electro -percussive 
methods.  Electric  welding  was  first  introduced  by  Elihu 
Thomson  in  1886,  his  process  of  incandescent  welding  consisting 
in  passing  a  heavy  alternating  current  through  the  pieces  to  be 
welded,  the  increased  resistance  at  their  point  of  contact  (contact 
welding)  giving  the  necessary  temperature  at  the  joint.  Other 
contact  systems  were  devised  by  Pontelec,  Helsby,  and  Lagrange- 
Hoho.  In  Bernardos'  process  an  arc  is  formed  between  a  carbon 
rod  (positive  pole)  and  the  metal  (negative  pole).  Between  the 
pieces  to  be  welded  are  placed  small  pieces  of  metal,  such  as 
turnings,  which  melt  and  unite  the  pieces  by  soldering  rather  than 
by  true  welding.  Bernardos  also  suggested  the  application  of  a 
magnet  to  deflect  the  arc  between  two  electrodes,  forming  an 
electric  blast.  This  method  (voltex  process)  was  prefected  in  the 
Zerener  process.  Somewhat  similar  to  Bernardos'  earlier 
method  was  that  of  N.  Slaviankoff  for  repairing  broken  pieces  of 
machinery,  etc.  The  piece  to  be  repaired  is  attached  directly 
to  one  pole  of  a  dynamo,  and  small  pieces  of  metal  are  melted  by 


504  WELDING 

the  electric  arc  in  a  special  tool  attached  to  the  other  pole  and  fall 
on  the  object  in  a  molten  state. 

Spot  welding  is  the  fusing  or  welding  together  of  relatively  thin 
sections  by  means  of  a  single-phase  alternating  current,  with  the 
electrode  making  a  heavy  contact  pressure  on  the  area  being 
welded.  It  is  adapted  especially  to  sheet  metal  work  ranging 
from  the  welding  of  fish  plates  to  tram  rails,  to  the  lightest  of 
sections  such  as  the  sticking  of  handles  to  oil  cans  and  kitchen 
ware.  The  electrical  contacts  cover  a  small  area  similar  to  that 
of  a  rivet,  and,  the  points  pinch  the  two  pieces  together  like  a  vise. 
A _ heavy  current  is  then  sent  through  this  area  and  in  a  few 
minutes  produces  a  welding  heat.  It  can  be  made  to  take  the 
place  of  riveting,  requires  no  punching  and  is  much  quicker.  It 
can  be  applied  to  almost  all  kinds  of  metals  and  alloys  except 
that  cast  iron  cannot  be  welded  to  cast  iron.  It  is  also  possible 
to  heat  and  head  rivets  when  set  in  the  holes,  and  to  produce  soft 
spots  in  hardened  sheets  (Iron  Trade  Review,  Oct.  19,  1916,  781). 
Electro -percussive  welding  (also  called  percussive  electric 
welding)  is  a  recent  development  of  electrical  welding  originated 
by  L.  W.  Chubb.  The  process  is  based  on  the  principle  of  simul- 
taneous condenser  discharge  and  percussive  engagement.  In 
the  first  apparatus  the  wires  to  be  welded  together,  placed  in  the 
grips  of  two  hinged  arms,  were  connected  to  the  terminals  of  a 
charged  electrolytic  condenser.  When  the  arms  were  released 
the  wires  came  into  contact  and  immediately  discharged  the 
explosive  condenser,  the  force  of  impact  welding  the  ends  to- 
gether. In  an  improved  apparatus,  similar  in  construction  to  a 
pile  driver,  the  forge  effect  and  velocity  are  capable  of  independ- 
ent variation.  It  is  claimed  that  the  generation  of  heat  is  so 
localized,  so  sudden  and  so  intense,  that  there  is  no  time  for 
unequal  heat  conduction  through  the  shanks  of  the  wires,  and 
the  ends  will  be  melted  and  even  vaporized  whether  the  melting 
point  of  the  metal  is  high  or  low.  For  this  reason  various  metals 
and  alloys  can  be  welded  together  independently  of  their  electrical 
resistance,  melting  point,  or  heat  conductance  (Journ.  Inst. 
Metals,  1915,  II,  247).  ji«i 

Thermit  welds  are  those  where  (a)  the  temperature  is  secured 
by  contact  with  the  slag  produced  from  thermit  applied  around 
the  joint  and  may  in  cases  be  high  enough  to  cause  actual  or 
partial  fusion;  or  (b)  where  the  molten  metal  produced  from 
thermit  is  used  directly  to  form  the  joint.  The  Stroh  steel 
hardening  process  is  stated  to  consist  in  depositing  a  layer  of  alloy 
steel  to  secure  a  better  wearing  surface  and  may  be  of  a  depth 
as  required,  uniting  with  the  part  so  treated  (Iron  Age,  May  2, 
1912,  1080).  The  Simpson  weld,  intended  as  a  method  where 
high-speed  tool  steel  is  to  be  united  to  a  soft  steel  backing  for 
armor  plate,  etc.,  consists  in  the  application  of  a  section  of  copper 
between  the  two  sheets  of  steel;  a  mixture  of  charcoal,  brown 
sugar,  and  water  is  used  as  a  flux  and  upon  being  subjected  to  a 
temperature  of  2000°  F.  (1095°  G.)  the  copper  combines  with  the 
steel  and  forms  a  perfect  weld  (Iron  Trade  Rev.,  Aug.  17,  1911, 
286). 


WELDING  CINDER— WHEEL  SWARF  505 

Soldering  consists  in  joining  two  metals  or  alloys  together  by 
means  of  a  more  soluble  alloy  (solder)  or  one  to  which  they  will 
more  readily  unite  than  with  each  other.  Ordinary  or  soft  spider, 
used  for  uniting  non-ferrous  metals  such  as  lead,  or  principally 
sheets  of  iron  or  steel,  consists  of  approximately  2  parts  of  lead 
and  i  part  of  tin.  Wiping  (of  joints)  is  a  term  used  principally 
in  plumbing  work  where  the  solder  in  a  pasty,  semi-molten  condi- 
tion is  worked  and  pressed  into  the  desired  shape  around  a  joint. 
Hard  solder  consists  of  a  mixture  of  copper  and  zinc,  usually 
about  half  and  half,  sometimes  with  a  little  tin  added,  and  is  used 
for  brazing  or  joining  where  greater  strength  is  required  than  by 
soldering  but  not  so  great  as  by  welding.  Autogenous  welding  or 
soldering  is  really  a  form  of  soldering  where  two  pieces  of  the 
same  metal,  or  alloy  are  united  by  limited  fusion  of  the  pieces 
themselves  without  the  addition  of  some  other  substance  (except 
a  flux).  The  autogenous  welding  of  lead  pipe  is  sometimes  called 
lead  burning. 

Welding  Cinder. — See  page  501. 

Welding  Flux. — See  page  501. 

Welding  Furnace. — (i)  A  furnace  in  which  pieces  are  heated  for 
welding;  (2)  a  puddling  furnace  (obs.). 

Welding  Heat. — See  page  501. 

Welding  Plate. —See  age  pso2. 

Welding  Process. — Of  coating:  see  page  372. 

Welding  Seam. — See  page  502. 

Welding  Temperature. — See  page  501. 

Weldless  Tube. — See  page  490. 

Well. — Hearth  of  a  blast  furnace:  see  page  27. 

Wellman  and  Schwab  Process. — See  page  388. 

Welt. — The  covering  strip  used  in  butt  riveting  (Homer). 

Wenstrom  Mill. — See  page  420. 

West  Coast  Hematite. — See  page  344. 

West  Sintering  Process. — See  page  45. 

Westman  Process. — See  page  148. 

Westphalia  Gage. — See  page  188. 

Wet  Analysis. — See  page  82. 

Wet  Assaying. — See  page  82. 

Wet  Blacking.— See  page  298. 

Wet  Bottom.— See  pages  253  and  377. 

Wet  Brush.— See  page  298. 

Wet  Cleaning. — Of  gas:  see  page  33. 

Wet  Drawing. — See  page  508. 

Wet  Process.— See  page  82. 

Wet  Puddling.— See  page  374. 

Wet  Slag.— See  Slag. 

Wet  Washing.— Of  gas:  see- page  33. 

Weyl's  Method.— Of  etching:  see  page  288. 

Weyrauch's  Formula. — For  tensile  strength:  see  page  339. 

Wheel  Breaker.— See  page  481. 

Wheel  Burns. — See  page  1 10. 

Wheel  Swarf  (Eng.). — A  mixture  of  silicious  particles  and  partially 
rusted  steel  obtained  from  the  grindstones  in  cutlery  grinding;  it 


$o6  WHEELER  PROCESS— WIND  BOX 

is  used  in  cementation  furnaces  as  a  lute  to  make  the  pots  air- 
tight. 

Wheeler  Process. — See  page  64. 

Wheeling  Theory.— Of  slip:  see  page  284. 

Whiskers. — Of  coke:  see  page  96. 

White  Amorphous  Sulphur. — See  Sulphur. 

White  Annealing. — See  page  431. 

White  Calorimeter. — See  page  201. 

White  Cast  Iron. — See  page  342. 

White  Clay. — See  page  302. 

White  Crucible  Process. — See  page  114. 

White  Edged  Plate. — See  page  432. 

White  Ghost  Lines. — See  page  289. 

White  Heart  Casting;  Malleable. — See  page  258. 

White  Heat. — Color  temperature:  see  page  210. 

White  Iron. — (i)  Grade  of  pig  iron:  see  page  342;  (2)  tin  plate:  see 
page  433. 

White  Iron  Pyrites. — See  page  245. 

White  Ironstone. — See  page  244. 

White  Metal.— See  page  383. 

White  Pickling. — See  page  431. 

White  Pig. — See  page  342. 

White  Pot. — (i)  Kind  of  crucible:  see  page  in;  (2)  in  the  manu- 
facture of  tin  plate:  see  page  431. 

White  Refined  Cast  Iron.— See  page  383. 

White-Souther  Machine. — See  page  482. 

Whiteley  Process. — See  page  65. 

Whiteley's  Reagent. — For  etching:  see  page  287. 

Whitesmith. — See  page  433. 

Whitworth  Armor  Plate. — See  page  9. 

Whitworth  Process. — For  fluid  compression:  see  page  63. 

Wiborgh  Air  Pyrometer. — See  page  207. 

Wiborgh's  Thermophone. — See  page  210. 

Wicket. — The  small  hole  in  the  door  of  an  open  hearth  or  other 
form  of  furnace  through  which  the  interior  can  be  inspected  with- 
out raising  the  door. 

Widmanstatten  (Widmanstattian)  Lines;  Structure. — See  page  291. 

Wild. — Of  metal,  usually  steel,  when  overoxidized,  causing  it  to 
spit  and  fly.  Spitting  in  the  ladle  is  usually  caused  by  a  reaction 
between  the  metal  and  the  cinder;  in  the  molds,  by  the  violent 
escape  of  gases  while  the  metal  is  in  a  pasty  condition.  The 
opposite  condition  is  dead. 

Wild  Process. — See  page  64. 

Wile  Furnace. — See  page  165. 

Willans  Process. — See  page  388. 

Williams  Mill. — See  page  420.  ;;:*:.?.; 

Williams  Process. — See  page  63. 

Willis  Process.— See  page  372. 

Wills  Converter. — See  page  25. 

Wilson  Process. — For  armor  plate:  see  page  9;  (2)  direct  process: 
see  page  148. 

Wind  Box. — See  page  17. 


WIND  FURNACE— WIRE  507 

Wind  Furnace. — See  page  183. 

Winiwarter  Process. — See  page  370. 

Winslow  Squeezer. — See  page  377.    % 

Wiper. — In  wire  manufacture:  see  page  509. 

Wiping. — Kind  of  soldering:  see  page  505. 

Wire. — On  tinned  sheets:  see  page  432. 

Wire. — (i)  The  name  given  to  small  metal  filaments  (usually  round) 
produced  in  pieces  of  considerable  length  by  drawing,  i.e.,  suc- 
cessively reducing  (and  thereby  extending)  the  section  by 
repeatedly  pulling  it  cold  (cold  drawing)  through  tapered  holes 
in  a  die  or  draw  plate  (block,  die  plate).  Drawing  is  necessary 
as  it  is  impracticable  to  roll  such  small  sections  commercially. 
(2)  Wire  is  also  the  name  given  to  rounds  for  helical  springs 
(particularly  for  railway  work). 

Billets  are  first  reduced,  in  a  rolling  mill,  to  wire  rods  (rounds) 
about  0.2"  to  0.3"  in  diameter,  which  are  coiled  up  into  bundles. 

.  These  bundles  are  placed  in  a  pickling  bath  of  dilute  sulphuric 
acid,  heated  by  steam,  to  remove  the  scale,  and  are  then  trans- 
ferred to  the  rinsing  bath  to  remove  the  greater  part  of  the  acid, 
after  which  they  are  put  on  a  revolving  frame  and  sprayed 
with  water  still  further  to  remove  the  acid;  this  causes  a  certain 
amount  of  rust  to  form  on  the  surface,  which  acts  later  as  a 
slight  lubricant  and  is  known  as  a  rust  coating,  water  coating,  or 
sull. 

The  last  traces  of  acid  are  eliminated  by  treatment  in  the 
lime  bath  (Inning),  after  which  the  bundles  are  taken  to  the 
dry  house  where  they  are  dried  (baked)  at  a  low  temperature  in 
a  furnace  called  the  baker.  This  treatment  expels  most  of  the 
occluded  hydrogen  (due  to  the  action  of  the  acid)  whose  presence 
causes  brittleness  (acid  brittleness).  If  the  wire  is  to  be  bright 
finished  (i.e.,  unannealed),  it  is  transferred  from  the  rinsing 
bath  immediately  to  the  lime  bath.  Instead  of  cleaning  wire 
with  acid,  it  is  sometimes  put  into  a  scouring  barrel,  in  which  it  is 
rotated  with  some  cleaning  material. 

The  draw  plate  is  either  of  chilled  cast  iron  or  of  steel.  Accord- 
ing to  Lewis  (Iron  Trade  Review,  Oct.  9,  1913)  the  former  is  most 
largely  used  in  this  country,  and  is  prepared  by  reaming  out  the 
hole  which,  when  worn,  must  be  enlarged  to  the  next  size.  The 
latter,  generally  used  in  Europe,  is  made  of  the  best  grade  of  tool 
steel  (high  carbon),  and  when  worn  is  upset  to  a  smaller  size  by 
gently  hammering  around  the  hole  and  then  reaming  out  again  to 
the  original  size;  as  this  cold  upsetting  hardens  the  metal,  it  is 
carefully  annealed  from  time  to  time.  Some  steel  dies  are  also 
quenched  to  contract  the  hole.  The  term  hole  or  draw  hole 
(through  which  the  wire  passes  for  reduction)  signifies  the  entire 
aperture.  This  is  somewhat  enlarged  at  the  two  surfaces  of  the 
plate,  and  the  part  of  smallest  diameter  where  the  drawing  is 
principally  accomplished  is  distinguished  as  the  gage  hole. 
Usually  all  the  holes  in  one  plate  are  of  the  same  size  and  the 
wire  is  passed  through  successive  plates,  each  hole  serving  for  one 
(sometimes  two)  bundle.  After  use  the  plates  are  annealed  (as 
the  metal  around  the  holes  has  been  hardened),  the  holes  reduced 


5o8  WIRE 

by  hammering  and  then  opened  up  to  the  exact  size  by  punching 
(pricking).  The  plates  used  for  the  first  few  reductions  are 
sometimes  referred  to  as  the  roughing  blocks,  ripping  blocks,  or 
rippers,  those  for  the  last,  as  finishing  blocks. 

Drawing  is  performed  on  the  draw  bench,  which  comprises 
the  draw  plate  and  a  power  reel  for  pulling  the  wire  through. 
To  start  the  wire  through  the  hole,  it  must  be  pointed  either 
with  a  small  hammer,  or  by  a  pair  of  small  rollers  with  grooves 
of  different  sizes,  given  a  rocking  movement  (like  an  alligator 
shears)  by  an  eccentric.  The  wire  is  then  .pulled  through  by 
a  pair  of  tongs  (grippers  or  nippers)  attached  to  a  crank  shaft, 
giving  a  reciprocating  (back  and  forth)  movement,  until  there 
is  a  sufficient  length  to  attach  it  to  the  power  reel.  The  term 
ratch  is  used  for  the  pull  of  the  wire  through  the  die  at  one  opera- 
tion where  a  straight  pull  and  not  a  reel  is  used.  The  plate 
is  sometimes  tilted  backward  at  a  slight  angle  to  kill  the  wire, 
i.e.,  prevent  the  tendency  to  spring  out  into  an  unmanageably, 
large  coil  on  removal  from  the  reel.  .To  reduce  the  friction  in 
drawing,  the  wire  must  be  coated  with  some  substance  which 
acts  as  a  lubricant.  In  dry  drawing,  grease  is  employed:  it 
is  piled  against  the  back  of  the  draw  plate  around  the  hole, 
and  one  application  serves  for  a  number  of  reductions.  In  wet 
drawing,  the  wire  is  given  a  lees  coating  by  passing  it  through 
lees  liquor  composed  of  water  and  some  kind  of  flour,  some- 
times fermented  and  sometimes  mixing  with  milk  of  lime.  A 
copper  coating  (lacquer)  is  obtained  by  treating  the  wire  with 
a  weak  acidulated  solution  of  copper  sulphate,  and  then  usually 
passing  it  through  lees  liquor  before  drawing.  After  this  treat- 
ment it  is  known  as  lacquered,  straw-tinted,  or  coppered  wire; 
this  method  is  sometimes  called  the  liquor -bright  process.  If 
the  finished  wire  is  to  be  coppered,  it  must  receive  an  additional 
treatment. 

Multiple  drawing  is  where  the  wire  is  drawn  through  a  num- 
ber of  dies  simultaneously,  being  reeled  up  only  after  passing 
through  the  last,  instead  of  after  each  plate.  In  this  case, 
to  avoid  breaking,  it  is  necessary  to  provide  a  power  reel  between 
each  pair  of  holes,  around  which  the. wire  is  given  a  couple  of 
turns.  Passing  the  wire  through  the  various  dies  and  around 
the  reels,  ready  for  drawing,  is  called  stringing  up.  After 
about  8  to  10  holes  (hole  in  this  sense  means  pass  or  reduction) 
the  wire  is  so  much  hardened  that  it  must  be  reannealed,  etc., 
before  drawing  can  be  continued.  This  fine  wire  is  sometimes 
batted,  i.e.,  beaten  with  wooden  sticks  while  being  washed  after 
pickling. 

Plain  drawn  wire  (bench  hardened  wire)  is  wire  in  the  con- 
dition in  which  it  leaves  the  last  hole,  without  any  further 
treatment.  Plain  annealed  wire  is  where  it  is  annealed  in 
closed  iron  pots  to  rended  it  soft  and  pliable.  Galvanized  wire 
is  annealed  and  then  coated  with  zinc  (spelter).  In  galvanizing, 
the  wire  is  passed  (a)  through  a  lead  bath  to  anneal  it;  (b)  through 
a  weak  pickling  solution  to  remove  the  scale  formed;  (c)  through 
a  rinsing  bath;  and  (d)  through  the  molten  spelter  contained  in  the 


WIRE— WIRE  GLASS  509 

galvanizing  pan.  The  excess  of  zinc  is  removed  by  drawing  it 
through  plugs  of  asbestos,  called  wipers.  The  wire  is  kept  below 
the  surface  of  the  zinc  by  passing  it  under  heavy  toothed  bars, 
called  sinkers.  In  modern  practice  a  number  of  wires  or  strands 
are  treated  simultaneously,  the  whole  series  of  operations  being 
continuous,  and  one  power  reel  serving  to  pull  each  strand 
through  (Bedspn's  continuous  galvanizing  process).  Bright 
annealed  wire  is  where  the  annealing  is  carefully  conducted  in 
closed  pots  to  keep  surface  oxidation  at  a  minimum;  attempts 
have  also  been  made  to  prevent  oxidation  entirely  by  means  of  a 
reducing  or  neutral  atmosphere. 

After  having  been  drawn  down  several  numbers,  i.e.,  reduced 
by  passing  through  several  successively  smaller  holes,  the  wire 
becomes  brittle  from  the  cold  working  and  to  permit  of  further 
reduction  is  given  a  process  annealing  or  works  annealing ;  this 
consists  in  heating  to  a  temperature,  which  may  be  below  the 
critical,  say  1100°  F.  (595°  C.),  and  holding  a  certain  length  of 
time  (Tinsley)  followed  by  slow  cooling.  Dead  soft  annealing, 
as  the  name  indicates,  is  where  extra  precautions  are  observed 
to  make  the  wire  specially  soft  for  subsequent  severe  bending  or 
cold  working  processes.  Improved  or  patented  wire  is  where 
medium  carbon  wire  (about  0.35  to  0.85%  carbon)  is  heated 
above  the  critical  point  and  cooled  rapidly  through  the  critical 
range,  the  operation  usually  being  continuous,  the  wire  passing 
through  the  heated  tubes  of  a  furnace  and  cooled  by  being 
brought  into  the  air  or  into  a  bath  of  molten  lead,  comparatively 
cool  but  seldom  below  700°  F.  (370°  C.).  Patenting  serves  to 
increase  the  ductility  and  permit  of  greater  subsequent  drawing 
down  than  is  the  case  with  annealing.  Higher  carbon  wire 
(say  0.65  to  i  %  carbon)  is  usually  treated  by  quenching  and 
tempering  (Tinsley,  Am.  I.  &  S.  Inst.,  1914). 

Tinman's  wire  is  a  soft  bright  drawn  wire  used  in  the  manufac- 
ture of  various  tin  plate  goods.  Plow  steel  wire  is  made  from  a 
fine  grade  of  high-carbon,  crucible  steel,  and  is  so  called  because 
it  was  originally  used  for  dragging  steam  plows.  Gun  screw  wire 
is  a  name  sometimes  employed  for  wire  made  from  a  high  grade 
of  refined  wrought  iron.  B.,  B.  B.,  E.  B.  B.  (best,  best  best,  extra 
best  best)  wire,  or  four-sided  charcoal  wire  were  grades  in 
England,  used  for  telegraphic  work,  made  of  fagots  composed 
of  puddled  billets«in  the  center,  and  four  flats  outside,  of  (a) 
best  best  puddled  iron,  (b)  or  top  and  bottom  of  charcoal  iron 
with  sides  of  best  best  puddled  iron  or  (c)  charcoal  iron  all 
around,  respectively.  Bimetallic  wire  is  usually  a  combination  of 
steel  center  with  copper  outside  ("copper  clad" — see  Protection, 
page  372).  Stranded  wire  is  another  name  for  wire  rope  or  cable. 

Wire  Drawing. — See  page  64. 

Wire-edged. — Usually  a  defect;  of  material  having  a  rough"  un- 
trimmed  edge. 

Wire  Gage. — See  page  188. 

Wire  Glass. — Also  called  armored  glass ;  sheets  of  glass  cast  around 
a  wire  netting  which  holds  the  glass 'together  in  case  it  becomes 
cracked  or  broken. 


510         WIRE  IRON— WORK  OF  DEFORMATION 

Wire  ton. — See  page  378. 

Wire  Rod. — See  page  507. 

Wire  Rod  Mill.— See  page  417. 

Witherow  Converter. — See  page  25. 

Wittgenstein  Mill. — See  page  434. 

Wittnufftt  Converter. — See  page  25. 

Wittorff's  Equilibrium  Diagram. — See  page  272. 

Wobble ;  Wobbler. — See  page  407. 

Wb'hler's  Law. — See  page  333. 

Wohler  Range;  Test.— See  page  482. 

Wolf  Furnace ;  Oven. — See  page  147. 

Wolframinium. — A  trade  name  for  a  special  alloy  of  aluminum 

containing  a  small  percentage  of  tungsten. 
Wolfram  Steels.— See  page  450. 
Wolframite. — See  page  245. 
Wood. — As  a  fuel,   this  is  used  in  metallurgy  practically  only 

for   drying   purposes.     It   consists    naturally   of   nearly   equal 

parts  of  cellulose  and   water.       A  sample  of  air-dried  wood 

showed : 


Carbon 40.0% 

Hydrogen 4.8 

Oxygen 32.8 

Nitrogen 0.8 

Ash -. 1.6 

Moisture 20.0 

Wood  Coal  (Eng.). — An  old  name  for  charcoal. 

Wood  Process. — See  page  369. 

Wootz. — Or  Indian  steel ;  it  is  manufactured  from  wrought  iron 
made  in  a  native  furnace  (India)  in  the  following  way  (Harbord 
and  Hall):  "Small  crucibles  of  refractory  clay  are  used,  in 
each  of  which  about  a  pound  of  metal  is  placed,  with  a  certain 
proportion  of  finely  chopped  wood.  The  crucibles  are  then 
covered  with  one  or  two  green  leaves  and  wetted  clay,  and 
placed  in  the  sun  to  dry.  When  the  plugs  have  hardened, 
twenty  to  twenty-four  of  the  crucibles  are  built  in  an  arched 
form,  on  the  bottom  of  a  small  blast  furnace,  blown  by  bellows, 
and  strongly  heated  for  two  or  three  hours.  The  furnace  is 
then  allowed  to  cool,  the  crucibles  taken  out  and  broken,  the 
steel  having  melted  down  to  a  rounded  button  at  the  bottom 
of  each  pot.  Probably  in  order  that  it  may  be  completely 
melted  the  steel  is  overcarburized,  and  before  drawing  out 
into  bars  the  buttons  are  heated  for  several  hours  in  a  charcoal 
fire,  urged  by  bellows,  to  a  temperature  not  much  below  their 
melting  point,  and  turned  over  before  the  blast,  so  that  the 
metal  may  be  partially  decarburized." 

Work. — The  mechanical  treatment  which  a  piece  receives  in  the 
process  of  manufacture. 

Work  Cold. — Of  a  blast  furnace:  see  page  35. 

Work  of  Deformation. — See  page  481. 


WORK  HARDNESS— WUTH  PROCESS  511 

Work  Hardness. — See  page  331. 

Work  the  Holes. — To  have  charge  of  a  crucible  furnace. 

Work  Hot. — Of  a  blast  furnace:  see  page  35. 

Working. — (i)  The  condition  of  an  operation  or  process,  e.g., 
"How  is  the  heat  working?";  (2)  to  stir  an  open  hearth  heat  with 
a  rod,  or  to  add  ore,  to  assist  in  the  oxidation  of  the  carbon  and 
impurities;  (3)  to  corrode,  as  when  a  heat  is  working  on  the  bottom 
or  lining  of  a  furnace;  (4)  operating  a  mine. 

Working  Anvil  Block. — See  Hammer. 

Working  Load ;  Strength. — See  page  468. 

Wring  Fit. — Of  a  bar,  etc.;  which  fits  a  coupling  or  other  piece  so 
accurately  that,  while  it  cannot  be  readily  slid  or  pushed  on,  it 
can  be  wrung  or  twisted  on  (Howe). 

Works  Annealing. — See  page  509. 

Wrought  Iron. — Also  called  malleable  iron  in  England;  iron 
low  in  carbon  produced  in  a  pasty  condition  (owing  to  the 
temperature  employed  being  too  low  to  render  it  fluid),  in 
consequence  of  which  a  small  percentage  of  slag  is  mechanically 
intermingled  with  it.  The  percentage  of  carbon  is  usually 
under  0.15%,  and  that  of  the  other  constituents  (not  including 
the  slag)  under  0.25%.  It  can  be  forged  or  rolled,  and  welded, 
but  is  not  appreciably  hardened  by  rapid  cooling  (quenching). 
It  is  made  by  the  puddling,  a  direct,  or  a  charcoal  hearth  process. 

Wrought  Steel. — (i)  Wrought  iron  containing  sufficient  carbon 
so  it  may  be  hardened  by  quenching;  (2)  rarely,  steel  which 
has  been  worked,  more  especially  hammered. 

Wulf  Oven. — See  page  147. 

Wiirtemberger  Process. — See  page  319. 

Wuth  Process. — See  page  319. 


X 

Xe. — Chemical  symbol  for  xenon:  see  page  84. 

X  Band. — See  page  127. 

X-Ray  Examination.— Of  metals:  see  page  285. 

Xble ;  Xible. — An  abbreviation  sometimes  used  for  crucible. 


512 


Yb. — Chemical  symbol  for  ytterbium:  see  page  84. 

Yt. — Chemical  symbol  for  yttrium:  see  page  84. 

Yarrow  Test. — See  page  482. 

Yates  Process. — See  page  148. 

Yatsevitch's  Reagent. — For  etching:  see  page  287. 

Yellow  Prussiate  of  Potash. — Commercial  potassium  ferrocyanide, 

K2Fe(CN)4. 

Yellow  Pyrites. — See  page  245. 
Yellow  Temper. — Oxide  color:  see  page  230. 
Yield  Point. — (i)  General:  see  pages  334  and  470;  (2)  by  scribe  or 

scriber  method:  see  page  470. 
Yield  Stress. — See  page  471. 
Yielding  Guard. — See  page  415. 
Young  Blowing. — In  Bessemer  practice:  see  page  21. 
Young  Iron. — See  page  376. 
Young's  Modulus. — see  page  334. 


33  513 


Zn. — Chemical  symbol  for  zinc,  q.v. 

Zr. — Chemical  symbol  for  Zirconium:  see  page  84. 

Zenzes  Converter. — See  page  25. 

Zerener  Process. — See  page  503. 

Zero  Calorie. — See  page  199. 

Zero  Point. — See  Curve. 

Zinc.— Zn;  at.  wt.,  65.5;  melt,  pt.,  420°  C.  (786°  F.);  boil,  pt., 
918°  C.  (1684°  F.);  sp.  gr.,  7.14.  It  is  rarely  if  ever  found  in 
the  uncombined  condition.  When  pure  it  is  a  crystalline, 
bluish  white  metal,  only  slightly  tarnished  on  exposure  to 
air,  and,  for  this  reason,  used  as  a  protective  coating,  the  proc- 
ess being  known  as  galvanizing  (see  pages  370,  431).  It  alloys 
with  iron  in  all  proportions,  but  is  rarely  found  in  iron  except 
as  an  impurity.  Cadmia,  also  called  philosopher's  wool,  is  a 
deposit  of  oxide  of  zinc  found  in  the  upper  part  of  a  blast  furnace 
in  which  ores  containing  traces  of  zinc  are  smelted. 

Zinc  Ashes. — The  oxidized  zinc  removed  from  the  surface  of  a 
galvanizing  bath. 

Zinc  Dust. — Oxide  of  zinc  produced  when  zinc  is  distilled;  used 
in  sherardizing:  see  page  371. 

Zinc  Etching. — See  page  287. 

Zinc  Plating. — See  page  390. 

Zinceisen. — Zinc  (from  a  galvanizing  bath)  of  inferior  quality,  due 
to  the  presence  of  iron. 

Zincing  (rare). —  Zinc  plating  or  galvanizing:  see  page  370. 

Zone. — (i)  In  cementing:  see  page  68;  (2)  of  carbon  deposition  in 
blast  furnace  practice:  see  page  36;  (3)  of  complete  fusion:  see 
page  36;  (4)  of  heat  interception:  see  page  36;  (5)  of  incipient 
fusion:  see  page  36;  (6)  of  slag  formation:  see  page  36. 


THIS  BOOK  IS  DUE  ON  THE  LAST 


THIS  BOOK* 


LD  21-3 


«•  v  •* 


392156 


UNIVERSITY  OF  CALIFORNIA  LIBRARY 


